Method and apparatus to enable segmented CSI reporting in wireless communication systems

ABSTRACT

A method for operating a user equipment (UE) for channel state information (CSI) feedback in a wireless communication system is provided. The method comprises receiving, from a base station (BS), CSI reference signals (CSI-RSs) and CSI feedback configuration information, estimating a channel based on the received CSI-RSs, determining, based on the estimated channel and the CSI feedback configuration information, a number of non-zero coefficients (K l   NZ ) for each layer (l) of a total number of υ layers, wherein υ≥1 is a rank value, and a sum of the K l   NZ  across each of the υ layers as a total number of non-zero coefficients (K NZ ), where K NZ =Σ l=1   υ K l   NZ . The method further comprises transmitting, to the BS, the CSI feedback including the K NZ  value over an uplink (UL) channel.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No.17/447,808, filed on Sep. 15, 2021, which is a continuation of U.S.patent application Ser. No. 16/740,171, filed on Jan. 10, 2020, now U.S.Pat. No. 11,128,354, which claims priority to U.S. Provisional PatentApplication No. 62/793,949, filed on Jan. 18, 2019, U.S. ProvisionalPatent Application No. 62/795,677, filed on Jan. 23, 2019, U.S.Provisional Patent Application No. 62/811,253, filed on Feb. 27, 2019,U.S. Provisional Patent Application No. 62/812,650, filed on Mar. 1,2019, U.S. Provisional Patent Application No. 62/817,076, filed on Mar.12, 2019, and U.S. Provisional Patent Application No. 62/831,383, filedon Apr. 9, 2019. The content of the above-identified patent documents isincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to wireless communicationsystems and more specifically to channel state information (CSI)feedback to represent a downlink channel.

BACKGROUND

Understanding and correctly estimating the channel between a userequipment (UE) and a base station (BS) (e.g., gNode B (gNB)) isimportant for efficient and effective wireless communication. In orderto correctly estimate the DL channel conditions, the gNB may transmitreference signal, e.g., CSI-RS, to the UE for DL channel measurement,and the UE may report (e.g., feedback) information about channelmeasurement, e.g., CSI, to the gNB. With this DL channel measurement,the gNB is able to select appropriate communication parameters toefficiently and effectively perform wireless data communication with theUE.

SUMMARY

Embodiments of the present disclosure provide methods and apparatusesfor CSI reporting in a wireless communication system.

In one embodiment, a UE for CSI feedback in a wireless communicationsystem is provided. The UE includes a transceiver configured to receive,from a BS, CSI reference signals (CSI-RSs) and CSI feedbackconfiguration information. The UE further includes a processor operablycoupled to the transceiver. The processor is configured to estimate achannel based on the received CSI-RSs, and determine, based on theestimated channel and the CSI feedback configuration information, anumber of non-zero coefficients (K_(l) ^(NZ)) for each layer (l) of atotal number of υ layers, wherein υ≥1 is a rank value, and a sum of theK_(l) ^(NZ) across each of the υ layers as a total number of non-zerocoefficients (K^(NZ)), where K^(NZ)=Σ_(l=1) ^(υ)K_(l) ^(NZ). Thetransceiver is further configured to transmit, to the BS, the CSIfeedback including a value for the K^(NZ) over an uplink (UL) channel.

In another embodiment, a BS in a wireless communication system isprovided. The BS includes a processor configured to generate CSIfeedback configuration information. The BS further includes atransceiver operably coupled to the processor. The transceiver isconfigured to transmit, to a UE, CSI-RSs and the CSI feedbackconfiguration information, and receive, from the UE over an UL channel,a CSI feedback including a value for a total number of non-zerocoefficients (K^(NZ)) that is a sum of a number of non-zero coefficients(K_(l) ^(NZ)) across each layer (l) of a total number of υ layers, wherethe CSI feedback is based on the CSI-RSs and the CSI feedbackconfiguration information, K^(NZ)=Σ_(l=1) ^(υ)K_(l) ^(NZ), K_(l) ^(NZ)is number of non-zero coefficients for layer l, and υ≥1 is a rank value.

In yet another embodiment, a method for operating a UE for CSI feedbackin a wireless communication system is provided. The method comprisesreceiving, from a BS, CSI reference signals (CSI-RSs) and CSI feedbackconfiguration information, estimating a channel based on the receivedCSI-RSs, determining, based on the estimated channel and the CSIfeedback configuration information, a number of non-zero coefficients(K_(l) ^(NZ)) for each layer (l) of a total number of υ layers, whereinυ≥1 is a rank value, and a sum of the K_(l) ^(NZ) across each of the υlayers as a total number of non-zero coefficients (K^(NZ)), whereK^(NZ)=Σ_(l=1) ^(υ)K_(l) ^(NZ), and transmitting, to the BS, the CSIfeedback including the K^(NZ) value over an UL channel.

Other technical features may be readily apparent to one skilled in theart from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document. The term “couple” and its derivativesrefer to any direct or indirect communication between two or moreelements, whether or not those elements are in physical contact with oneanother. The terms “transmit,” “receive,” and “communicate,” as well asderivatives thereof, encompass both direct and indirect communication.The terms “include” and “comprise,” as well as derivatives thereof, meaninclusion without limitation. The term “or” is inclusive, meaningand/or. The phrase “associated with,” as well as derivatives thereof,means to include, be included within, interconnect with, contain, becontained within, connect to or with, couple to or with, be communicablewith, cooperate with, interleave, juxtapose, be proximate to, be boundto or with, have, have a property of, have a relationship to or with, orthe like. The term “controller” means any device, system or part thereofthat controls at least one operation. Such a controller may beimplemented in hardware or a combination of hardware and software and/orfirmware. The functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely. Thephrase “at least one of,” when used with a list of items, means thatdifferent combinations of one or more of the listed items may be used,and only one item in the list may be needed. For example, “at least oneof: A, B, and C” includes any of the following combinations: A, B, C, Aand B, A and C, B and C, and A and B and C.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughoutthis patent document. Those of ordinary skill in the art shouldunderstand that in many if not most instances, such definitions apply toprior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure;

FIG. 2 illustrates an example gNB according to embodiments of thepresent disclosure;

FIG. 3 illustrates an example UE according to embodiments of the presentdisclosure;

FIG. 4A illustrates a high-level diagram of an orthogonal frequencydivision multiple access transmit path according to embodiments of thepresent disclosure;

FIG. 4B illustrates a high-level diagram of an orthogonal frequencydivision multiple access receive path according to embodiments of thepresent disclosure;

FIG. 5 illustrates a transmitter block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 6 illustrates a receiver block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 7 illustrates a transmitter block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 8 illustrates a receiver block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 9 illustrates an example multiplexing of two slices according toembodiments of the present disclosure;

FIG. 10 illustrates an example antenna blocks according to embodimentsof the present disclosure;

FIG. 11 illustrates an example network configuration according toembodiments of the present disclosure;

FIG. 12 illustrates an antenna port layout according to embodiments ofthe present disclosure;

FIG. 13 illustrates a 3D grid of oversampled DFT beams according toembodiments of the present disclosure;

FIG. 14 illustrates a flow chart of a method for transmitting an ULtransmission including CSI feedback, as may be performed by a UEaccording to embodiments of the present disclosure; and

FIG. 15 illustrates a flow chart of another method for receiving an ULtransmission including CSI feedback, as may be performed by a BS,according to embodiments of the present disclosure.

DETAILED DESCRIPTION

FIGS. 1 through FIG. 15 , discussed below, and the various embodimentsused to describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The following documents and standards descriptions are herebyincorporated by reference into the present disclosure as if fully setforth herein: 3GPP TS 36.211 v15.8.0, “E-UTRA, Physical channels andmodulation;” 3GPP TS 36.212 v15.8.0, “E-UTRA, Multiplexing and Channelcoding;” 3GPP TS 36.213 v15.8.0, “E-UTRA, Physical Layer Procedures;”3GPP TS 36.321 v15.8.0, “E-UTRA, Medium Access Control (MAC) protocolspecification;” 3GPP TS 36.331 v15.8.0, “E-UTRA, Radio Resource Control(RRC) protocol specification;” 3GPP TR 22.891 v14.2.0; 3GPP TS 38.211v15.7.0, “E-UTRA, NR, Physical channels and modulation;” 3GPP TS 38.213v15.7.0, “E-UTRA, NR, Physical Layer Procedures for control;” 3GPP TS38.214 v15.7.0, “E-UTRA, NR, Physical layer procedures for data;” and3GPP TS 38.212 v15.7.0, “E-UTRA, NR, Multiplexing and channel coding.”

Aspects, features, and advantages of the disclosure are readily apparentfrom the following detailed description, simply by illustrating a numberof particular embodiments and implementations, including the best modecontemplated for carrying out the disclosure. The disclosure is alsocapable of other and different embodiments, and its several details canbe modified in various obvious respects, all without departing from thespirit and scope of the disclosure. Accordingly, the drawings anddescription are to be regarded as illustrative in nature, and not asrestrictive. The disclosure is illustrated by way of example, and not byway of limitation, in the figures of the accompanying drawings.

In the following, for brevity, both FDD and TDD are considered as theduplex method for both DL and UL signaling.

Although exemplary descriptions and embodiments to follow assumeorthogonal frequency division multiplexing (OFDM) or orthogonalfrequency division multiple access (OFDMA), the present disclosure canbe extended to other OFDM-based transmission waveforms or multipleaccess schemes such as filtered OFDM (F-OFDM).

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a “beyond 4G network” or a“post LTE system.”

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higherdata rates. To decrease propagation loss of the radio waves and increasethe transmission coverage, the beamforming, massive multiple-inputmultiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques and the like arediscussed in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul communication, moving network,cooperative communication, coordinated multi-points (CoMP) transmissionand reception, interference mitigation and cancellation and the like.

In the 5G system, hybrid frequency shift keying and quadrature amplitudemodulation (FQAM) and sliding window superposition coding (SWSC) as anadaptive modulation and coding (AMC) technique, and filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), and sparse codemultiple access (SCMA) as an advanced access technology have beendeveloped.

FIGS. 1-4B below describe various embodiments implemented in wirelesscommunications systems and with the use of orthogonal frequency divisionmultiplexing (OFDM) or orthogonal frequency division multiple access(OFDMA) communication techniques. The descriptions of FIGS. 1-3 are notmeant to imply physical or architectural limitations to the manner inwhich different embodiments may be implemented. Different embodiments ofthe present disclosure may be implemented in any suitably-arrangedcommunications system. The present disclosure covers several componentswhich can be used in conjunction or in combination with one another, orcan operate as standalone schemes.

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure. The embodiment of the wireless network shownin FIG. 1 is for illustration only. Other embodiments of the wirelessnetwork 100 could be used without departing from the scope of thisdisclosure.

As shown in FIG. 1 , the wireless network includes a gNB 101, a gNB 102,and a gNB 103. The gNB 101 communicates with the gNB 102 and the gNB103. The gNB 101 also communicates with at least one network 130, suchas the Internet, a proprietary Internet Protocol (IP) network, or otherdata network.

The gNB 102 provides wireless broadband access to the network 130 for afirst plurality of user equipments (UEs) within a coverage area 120 ofthe gNB 102. The first plurality of UEs includes a UE 111, which may belocated in a small business (SB); a UE 112, which may be located in anenterprise (E); a UE 113, which may be located in a WiFi hotspot (HS); aUE 114, which may be located in a first residence (R); a UE 115, whichmay be located in a second residence (R); and a UE 116, which may be amobile device (M), such as a cell phone, a wireless laptop, a wirelessPDA, or the like. The gNB 103 provides wireless broadband access to thenetwork 130 for a second plurality of UEs within a coverage area 125 ofthe gNB 103. The second plurality of UEs includes the UE 115 and the UE116. In some embodiments, one or more of the gNBs 101-103 maycommunicate with each other and with the UEs 111-116 using 5G, LTE,LTE-A, WiMAX, WiFi, or other wireless communication techniques.

Depending on the network type, the term “base station” or “BS” can referto any component (or collection of components) configured to providewireless access to a network, such as transmit point (TP),transmit-receive point (TRP), an enhanced base station (eNodeB or eNB),a 5G base station (gNB), a macrocell, a femtocell, a WiFi access point(AP), or other wirelessly enabled devices. Base stations may providewireless access in accordance with one or more wireless communicationprotocols, e.g., 5G 3GPP new radio interface/access (NR), long termevolution (LTE), LTE advanced (LTE-A), high speed packet access (HSPA),Wi-Fi 802.11a/b/g/n/ac, etc. For the sake of convenience, the terms “BS”and “TRP” are used interchangeably in this patent document to refer tonetwork infrastructure components that provide wireless access to remoteterminals. Also, depending on the network type, the term “userequipment” or “UE” can refer to any component such as “mobile station,”“subscriber station,” “remote terminal,” “wireless terminal,” “receivepoint,” or “user device.” For the sake of convenience, the terms “userequipment” and “UE” are used in this patent document to refer to remotewireless equipment that wirelessly accesses a BS, whether the UE is amobile device (such as a mobile telephone or smartphone) or is normallyconsidered a stationary device (such as a desktop computer or vendingmachine).

Dotted lines show the approximate extents of the coverage areas 120 and125, which are shown as approximately circular for the purposes ofillustration and explanation only. It should be clearly understood thatthe coverage areas associated with gNBs, such as the coverage areas 120and 125, may have other shapes, including irregular shapes, dependingupon the configuration of the gNBs and variations in the radioenvironment associated with natural and man-made obstructions.

As described in more detail below, one or more of the UEs 111-116include circuitry, programing, or a combination thereof, for an ULtransmission based on an UL codebook in an advanced wirelesscommunication system. In certain embodiments, and one or more of thegNBs 101-103 includes circuitry, programing, or a combination thereof,for CSI acquisition in an advanced wireless communication system.

Although FIG. 1 illustrates one example of a wireless network, variouschanges may be made to FIG. 1 . For example, the wireless network couldinclude any number of gNBs and any number of UEs in any suitablearrangement. Also, the gNB 101 could communicate directly with anynumber of UEs and provide those UEs with wireless broadband access tothe network 130. Similarly, each gNB 102-103 could communicate directlywith the network 130 and provide UEs with direct wireless broadbandaccess to the network 130. Further, the gNBs 101, 102, and/or 103 couldprovide access to other or additional external networks, such asexternal telephone networks or other types of data networks.

FIG. 2 illustrates an example gNB 102 according to embodiments of thepresent disclosure. The embodiment of the gNB 102 illustrated in FIG. 2is for illustration only, and the gNBs 101 and 103 of FIG. 1 could havethe same or similar configuration. However, gNBs come in a wide varietyof configurations, and FIG. 2 does not limit the scope of thisdisclosure to any particular implementation of a gNB.

As shown in FIG. 2 , the gNB 102 includes multiple antennas 205 a-205 n,multiple RF transceivers 210 a-210 n, transmit (TX) processing circuitry215, and receive (RX) processing circuitry 220. The gNB 102 alsoincludes a controller/processor 225, a memory 230, and a backhaul ornetwork interface 235.

The RF transceivers 210 a-210 n receive, from the antennas 205 a-205 n,incoming RF signals, such as signals transmitted by UEs in the network100. The RF transceivers 210 a-210 n down-convert the incoming RFsignals to generate IF or baseband signals. The IF or baseband signalsare sent to the RX processing circuitry 220, which generates processedbaseband signals by filtering, decoding, and/or digitizing the basebandor IF signals. The RX processing circuitry 220 transmits the processedbaseband signals to the controller/processor 225 for further processing.

The TX processing circuitry 215 receives analog or digital data (such asvoice data, web data, e-mail, or interactive video game data) from thecontroller/processor 225. The TX processing circuitry 215 encodes,multiplexes, and/or digitizes the outgoing baseband data to generateprocessed baseband or IF signals. The RF transceivers 210 a-210 nreceive the outgoing processed baseband or IF signals from the TXprocessing circuitry 215 and up-converts the baseband or IF signals toRF signals that are transmitted via the antennas 205 a-205 n.

The controller/processor 225 can include one or more processors or otherprocessing devices that control the overall operation of the gNB 102.For example, the controller/processor 225 could control the reception offorward channel signals and the transmission of reverse channel signalsby the RF transceivers 210 a-210 n, the RX processing circuitry 220, andthe TX processing circuitry 215 in accordance with well-knownprinciples. The controller/processor 225 could support additionalfunctions as well, such as more advanced wireless communicationfunctions.

For instance, the controller/processor 225 could support beam forming ordirectional routing operations in which outgoing signals from multipleantennas 205 a-205 n are weighted differently to effectively steer theoutgoing signals in a desired direction. Any of a wide variety of otherfunctions could be supported in the gNB 102 by the controller/processor225.

The controller/processor 225 is also capable of executing programs andother processes resident in the memory 230, such as an OS. Thecontroller/processor 225 can move data into or out of the memory 230 asrequired by an executing process.

The controller/processor 225 is also coupled to the backhaul or networkinterface 235. The backhaul or network interface 235 allows the gNB 102to communicate with other devices or systems over a backhaul connectionor over a network. The interface 235 could support communications overany suitable wired or wireless connection(s). For example, when the gNB102 is implemented as part of a cellular communication system (such asone supporting 5G, LTE, or LTE-A), the interface 235 could allow the gNB102 to communicate with other gNBs over a wired or wireless backhaulconnection. When the gNB 102 is implemented as an access point, theinterface 235 could allow the gNB 102 to communicate over a wired orwireless local area network or over a wired or wireless connection to alarger network (such as the Internet). The interface 235 includes anysuitable structure supporting communications over a wired or wirelessconnection, such as an Ethernet or RF transceiver.

The memory 230 is coupled to the controller/processor 225. Part of thememory 230 could include a RAM, and another part of the memory 230 couldinclude a Flash memory or other ROM.

Although FIG. 2 illustrates one example of gNB 102, various changes maybe made to FIG. 2 . For example, the gNB 102 could include any number ofeach component shown in FIG. 2 . As a particular example, an accesspoint could include a number of interfaces 235, and thecontroller/processor 225 could support routing functions to route databetween different network addresses. As another particular example,while shown as including a single instance of TX processing circuitry215 and a single instance of RX processing circuitry 220, the gNB 102could include multiple instances of each (such as one per RFtransceiver). Also, various components in FIG. 2 could be combined,further subdivided, or omitted and additional components could be addedaccording to particular needs.

FIG. 3 illustrates an example UE 116 according to embodiments of thepresent disclosure. The embodiment of the UE 116 illustrated in FIG. 3is for illustration only, and the UEs 111-115 of FIG. 1 could have thesame or similar configuration. However, UEs come in a wide variety ofconfigurations, and FIG. 3 does not limit the scope of this disclosureto any particular implementation of a UE.

As shown in FIG. 3 , the UE 116 includes an antenna 305, a radiofrequency (RF) transceiver 310, TX processing circuitry 315, amicrophone 320, and receive (RX) processing circuitry 325. The UE 116also includes a speaker 330, a processor 340, an input/output (I/O)interface (IF) 345, a touchscreen 350, a display 355, and a memory 360.The memory 360 includes an operating system (OS) 361 and one or moreapplications 362.

The RF transceiver 310 receives, from the antenna 305, an incoming RFsignal transmitted by a gNB of the network 100. The RF transceiver 310down-converts the incoming RF signal to generate an intermediatefrequency (IF) or baseband signal. The IF or baseband signal is sent tothe RX processing circuitry 325, which generates a processed basebandsignal by filtering, decoding, and/or digitizing the baseband or IFsignal. The RX processing circuitry 325 transmits the processed basebandsignal to the speaker 330 (such as for voice data) or to the processor340 for further processing (such as for web browsing data).

The TX processing circuitry 315 receives analog or digital voice datafrom the microphone 320 or other outgoing baseband data (such as webdata, e-mail, or interactive video game data) from the processor 340.The TX processing circuitry 315 encodes, multiplexes, and/or digitizesthe outgoing baseband data to generate a processed baseband or IFsignal. The RF transceiver 310 receives the outgoing processed basebandor IF signal from the TX processing circuitry 315 and up-converts thebaseband or IF signal to an RF signal that is transmitted via theantenna 305.

The processor 340 can include one or more processors or other processingdevices and execute the OS 361 stored in the memory 360 in order tocontrol the overall operation of the UE 116. For example, the processor340 could control the reception of forward channel signals and thetransmission of reverse channel signals by the RF transceiver 310, theRX processing circuitry 325, and the TX processing circuitry 315 inaccordance with well-known principles. In some embodiments, theprocessor 340 includes at least one microprocessor or microcontroller.

The processor 340 is also capable of executing other processes andprograms resident in the memory 360, such as processes for CSI feedbackon uplink channel. The processor 340 can move data into or out of thememory 360 as required by an executing process. In some embodiments, theprocessor 340 is configured to execute the applications 362 based on theOS 361 or in response to signals received from gNBs or an operator. Theprocessor 340 is also coupled to the I/O interface 345, which providesthe UE 116 with the ability to connect to other devices, such as laptopcomputers and handheld computers. The I/O interface 345 is thecommunication path between these accessories and the processor 340.

The processor 340 is also coupled to the touchscreen 350 and the display355. The operator of the UE 116 can use the touchscreen 350 to enterdata into the UE 116. The display 355 may be a liquid crystal display,light emitting diode display, or other display capable of rendering textand/or at least limited graphics, such as from web sites.

The memory 360 is coupled to the processor 340. Part of the memory 360could include a random access memory (RAM), and another part of thememory 360 could include a Flash memory or other read-only memory (ROM).

Although FIG. 3 illustrates one example of UE 116, various changes maybe made to FIG. 3 . For example, various components in FIG. 3 could becombined, further subdivided, or omitted and additional components couldbe added according to particular needs. As a particular example, theprocessor 340 could be divided into multiple processors, such as one ormore central processing units (CPUs) and one or more graphics processingunits (GPUs). Also, while FIG. 3 illustrates the UE 116 configured as amobile telephone or smartphone, UEs could be configured to operate asother types of mobile or stationary devices.

FIG. 4A is a high-level diagram of transmit path circuitry. For example,the transmit path circuitry may be used for an orthogonal frequencydivision multiple access (OFDMA) communication. FIG. 4B is a high-leveldiagram of receive path circuitry. For example, the receive pathcircuitry may be used for an orthogonal frequency division multipleaccess (OFDMA) communication. In FIGS. 4A and 4B, for downlinkcommunication, the transmit path circuitry may be implemented in a basestation (gNB) 102 or a relay station, and the receive path circuitry maybe implemented in a user equipment (e.g., user equipment 116 of FIG. 1). In other examples, for uplink communication, the receive pathcircuitry 450 may be implemented in a base station (e.g., gNB 102 ofFIG. 1 ) or a relay station, and the transmit path circuitry may beimplemented in a user equipment (e.g., user equipment 116 of FIG. 1 ).

Transmit path circuitry comprises channel coding and modulation block405, serial-to-parallel (S-to-P) block 410, Size N Inverse Fast FourierTransform (IFFT) block 415, parallel-to-serial (P-to-S) block 420, addcyclic prefix block 425, and up-converter (UC) 430. Receive pathcircuitry 450 comprises down-converter (DC) 455, remove cyclic prefixblock 460, serial-to-parallel (S-to-P) block 465, Size N Fast FourierTransform (FFT) block 470, parallel-to-serial (P-to-S) block 475, andchannel decoding and demodulation block 480.

At least some of the components in FIGS. 4A 400 and 4B 450 may beimplemented in software, while other components may be implemented byconfigurable hardware or a mixture of software and configurablehardware. In particular, it is noted that the FFT blocks and the IFFTblocks described in this disclosure document may be implemented asconfigurable software algorithms, where the value of Size N may bemodified according to the implementation.

Furthermore, although this disclosure is directed to an embodiment thatimplements the Fast Fourier Transform and the Inverse Fast FourierTransform, this is by way of illustration only and may not be construedto limit the scope of the disclosure. It may be appreciated that in analternate embodiment of the present disclosure, the Fast FourierTransform functions and the Inverse Fast Fourier Transform functions mayeasily be replaced by discrete Fourier transform (DFT) functions andinverse discrete Fourier transform (IDFT) functions, respectively. Itmay be appreciated that for DFT and IDFT functions, the value of the Nvariable may be any integer number (i.e., 1, 4, 3, 4, etc.), while forFFT and IFFT functions, the value of the N variable may be any integernumber that is a power of two (i.e., 1, 2, 4, 8, 16, etc.).

In transmit path circuitry 400, channel coding and modulation block 405receives a set of information bits, applies coding (e.g., LDPC coding)and modulates (e.g., quadrature phase shift keying (QPSK) or quadratureamplitude modulation (QAM)) the input bits to produce a sequence offrequency-domain modulation symbols. Serial-to-parallel block 410converts (i.e., de-multiplexes) the serial modulated symbols to paralleldata to produce N parallel symbol streams where N is the IFFT/FFT sizeused in BS 102 and UE 116. Size N IFFT block 415 then performs an IFFToperation on the N parallel symbol streams to produce time-domain outputsignals. Parallel-to-serial block 420 converts (i.e., multiplexes) theparallel time-domain output symbols from Size N IFFT block 415 toproduce a serial time-domain signal. Add cyclic prefix block 425 theninserts a cyclic prefix to the time-domain signal. Finally, up-converter430 modulates (i.e., up-converts) the output of add cyclic prefix block425 to RF frequency for transmission via a wireless channel. The signalmay also be filtered at baseband before conversion to RF frequency.

The transmitted RF signal arrives at the UE 116 after passing throughthe wireless channel, and reverse operations to those at gNB 102 areperformed. Down-converter 455 down-converts the received signal tobaseband frequency, and remove cyclic prefix block 460 removes thecyclic prefix to produce the serial time-domain baseband signal.Serial-to-parallel block 465 converts the time-domain baseband signal toparallel time-domain signals. Size N FFT block 470 then performs an FFTalgorithm to produce N parallel frequency-domain signals.Parallel-to-serial block 475 converts the parallel frequency-domainsignals to a sequence of modulated data symbols. Channel decoding anddemodulation block 480 demodulates and then decodes the modulatedsymbols to recover the original input data stream.

Each of gNBs 101-103 may implement a transmit path that is analogous totransmitting in the downlink to user equipment 111-116 and may implementa receive path that is analogous to receiving in the uplink from userequipment 111-116. Similarly, each one of user equipment 111-116 mayimplement a transmit path corresponding to the architecture fortransmitting in the uplink to gNBs 101-103 and may implement a receivepath corresponding to the architecture for receiving in the downlinkfrom gNBs 101-103.

5G communication system use cases have been identified and described.Those use cases can be roughly categorized into three different groups.In one example, enhanced mobile broadband (eMBB) is determined to dowith high bits/sec requirement, with less stringent latency andreliability requirements. In another example, ultra reliable and lowlatency (URLL) is determined with less stringent bits/sec requirement.In yet another example, massive machine type communication (mMTC) isdetermined that a number of devices can be as many as 100,000 to 1million per km2, but the reliability/throughput/latency requirementcould be less stringent. This scenario may also involve power efficiencyrequirement as well, in that the battery consumption may be minimized aspossible.

A communication system includes a downlink (DL) that conveys signalsfrom transmission points such as base stations (BSs) or NodeBs to userequipments (UEs) and an Uplink (UL) that conveys signals from UEs toreception points such as NodeBs. A UE, also commonly referred to as aterminal or a mobile station, may be fixed or mobile and may be acellular phone, a personal computer device, or an automated device. AneNodeB, which is generally a fixed station, may also be referred to asan access point or other equivalent terminology. For LTE systems, aNodeB is often referred as an eNodeB.

In a communication system, such as LTE system, DL signals can includedata signals conveying information content, control signals conveying DLcontrol information (DCI), and reference signals (RS) that are alsoknown as pilot signals. An eNodeB transmits data information through aphysical DL shared channel (PDSCH). An eNodeB transmits DCI through aphysical DL control channel (PDCCH) or an Enhanced PDCCH (EPDCCH).

An eNodeB transmits acknowledgement information in response to datatransport block (TB) transmission from a UE in a physical hybrid ARQindicator channel (PHICH). An eNodeB transmits one or more of multipletypes of RS including a UE-common RS (CRS), a channel state informationRS (CSI-RS), or a demodulation RS (DMRS). A CRS is transmitted over a DLsystem bandwidth (BW) and can be used by UEs to obtain a channelestimate to demodulate data or control information or to performmeasurements. To reduce CRS overhead, an eNodeB may transmit a CSI-RSwith a smaller density in the time and/or frequency domain than a CRS.DMRS can be transmitted only in the BW of a respective PDSCH or EPDCCHand a UE can use the DMRS to demodulate data or control information in aPDSCH or an EPDCCH, respectively. A transmission time interval for DLchannels is referred to as a subframe and can have, for example,duration of 1 millisecond.

DL signals also include transmission of a logical channel that carriessystem control information. A BCCH is mapped to either a transportchannel referred to as a broadcast channel (BCH) when the DL signalsconvey a master information block (MIB) or to a DL shared channel(DL-SCH) when the DL signals convey a System Information Block (SIB).Most system information is included in different SIBs that aretransmitted using DL-SCH. A presence of system information on a DL-SCHin a subframe can be indicated by a transmission of a correspondingPDCCH conveying a codeword with a cyclic redundancy check (CRC)scrambled with system information RNTI (SI-RNTI). Alternatively,scheduling information for a SIB transmission can be provided in anearlier SIB and scheduling information for the first SIB (SIB-1) can beprovided by the MIB.

DL resource allocation is performed in a unit of subframe and a group ofphysical resource blocks (PRBs). A transmission BW includes frequencyresource units referred to as resource blocks (RBs). Each RB includesN_(SC) ^(RB) sub-carriers, or resource elements (REs), such as 12 REs. Aunit of one RB over one subframe is referred to as a PRB. A UE can beallocated M_(PDSCH) RBs for a total of M_(SC) ^(PDSCH)=M_(PDSCH)·N_(SC)^(RB) REs for the PDSCH transmission BW.

UL signals can include data signals conveying data information, controlsignals conveying UL control information (UCI), and UL RS. UL RSincludes DMRS and Sounding RS (SRS). A UE transmits DMRS only in a BW ofa respective PUSCH or PUCCH. An eNodeB can use a DMRS to demodulate datasignals or UCI signals. A UE transmits SRS to provide an eNodeB with anUL CSI. A UE transmits data information or UCI through a respectivephysical UL shared channel (PUSCH) or a Physical UL control channel(PUCCH). If a UE needs to transmit data information and UCI in a same ULsubframe, the UE may multiplex both in a PUSCH. UCI includes HybridAutomatic Repeat request acknowledgement (HARQ-ACK) information,indicating correct (ACK) or incorrect (NACK) detection for a data TB ina PDSCH or absence of a PDCCH detection (DTX), scheduling request (SR)indicating whether a UE has data in the UE's buffer, rank indicator(RI), and channel state information (CSI) enabling an eNodeB to performlink adaptation for PDSCH transmissions to a UE. HARQ-ACK information isalso transmitted by a UE in response to a detection of a PDCCH/EPDCCHindicating a release of semi-persistently scheduled PDSCH.

An UL subframe includes two slots. Each slot includes N_(symb) ^(UL)symbols for transmitting data information, UCI, DMRS, or SRS. Afrequency resource unit of an UL system BW is an RB. A UE is allocatedN_(RB) RBs for a total of N_(RB)·N_(SC) ^(RB) REs for a transmission BW.For a PUCCH, N_(RB)=1. A last subframe symbol can be used to multiplexSRS transmissions from one or more UEs. A number of subframe symbolsthat are available for data/UCI/DMRS transmission isN_(symb)=2·(N_(symb) ^(UL)−1)−N_(SRS), where N_(SRS)=1 if a lastsubframe symbol is used to transmit SRS and N_(SRS)=0 otherwise.

FIG. 5 illustrates a transmitter block diagram 500 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the transmitter block diagram 500 illustrated in FIG. 5 isfor illustration only. FIG. 5 does not limit the scope of thisdisclosure to any particular implementation of the transmitter blockdiagram 500.

As shown in FIG. 5 , information bits 510 are encoded by encoder 520,such as a turbo encoder, and modulated by modulator 530, for exampleusing quadrature phase shift keying (QPSK) modulation. A serial toparallel (S/P) converter 540 generates M modulation symbols that aresubsequently provided to a mapper 550 to be mapped to REs selected by atransmission BW selection unit 555 for an assigned PDSCH transmissionBW, unit 560 applies an Inverse fast Fourier transform (IFFT), theoutput is then serialized by a parallel to serial (P/S) converter 570 tocreate a time domain signal, filtering is applied by filter 580, and asignal transmitted 590. Additional functionalities, such as datascrambling, cyclic prefix insertion, time windowing, interleaving, andothers are well known in the art and are not shown for brevity.

FIG. 6 illustrates a receiver block diagram 600 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the diagram 600 illustrated in FIG. 6 is for illustrationonly. FIG. 6 does not limit the scope of this disclosure to anyparticular implementation of the diagram 600.

As shown in FIG. 6 , a received signal 610 is filtered by filter 620,REs 630 for an assigned reception BW are selected by BW selector 635,unit 640 applies a fast Fourier transform (FFT), and an output isserialized by a parallel-to-serial converter 650. Subsequently, ademodulator 660 coherently demodulates data symbols by applying achannel estimate obtained from a DMRS or a CRS (not shown), and adecoder 670, such as a turbo decoder, decodes the demodulated data toprovide an estimate of the information data bits 680. Additionalfunctionalities such as time-windowing, cyclic prefix removal,de-scrambling, channel estimation, and de-interleaving are not shown forbrevity.

FIG. 7 illustrates a transmitter block diagram 700 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 700 illustrated in FIG. 7 is forillustration only. FIG. 7 does not limit the scope of this disclosure toany particular implementation of the block diagram 700.

As shown in FIG. 7 , information data bits 710 are encoded by encoder720, such as a turbo encoder, and modulated by modulator 730. A discreteFourier transform (DFT) unit 740 applies a DFT on the modulated databits, REs 750 corresponding to an assigned PUSCH transmission BW areselected by transmission BW selection unit 755, unit 760 applies an IFFTand, after a cyclic prefix insertion (not shown), filtering is appliedby filter 770 and a signal transmitted 780.

FIG. 8 illustrates a receiver block diagram 800 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 800 illustrated in FIG. 8 is forillustration only. FIG. 8 does not limit the scope of this disclosure toany particular implementation of the block diagram 800.

As shown in FIG. 8 , a received signal 810 is filtered by filter 820.Subsequently, after a cyclic prefix is removed (not shown), unit 830applies a FFT, REs 840 corresponding to an assigned PUSCH reception BWare selected by a reception BW selector 845, unit 850 applies an inverseDFT (IDFT), a demodulator 860 coherently demodulates data symbols byapplying a channel estimate obtained from a DMRS (not shown), a decoder870, such as a turbo decoder, decodes the demodulated data to provide anestimate of the information data bits 880.

In next generation cellular systems, various use cases are envisionedbeyond the capabilities of LTE system. Termed 5G or the fifth generationcellular system, a system capable of operating at sub-6GHz and above-6GHz (for example, in mmWave regime) becomes one of the requirements. In3GPP TR 22.891, 74 5G use cases has been identified and described; thoseuse cases can be roughly categorized into three different groups. Afirst group is termed “enhanced mobile broadband (eMBB),” targeted tohigh data rate services with less stringent latency and reliabilityrequirements. A second group is termed “ultra-reliable and low latency(URLL)” targeted for applications with less stringent data raterequirements, but less tolerant to latency. A third group is termed“massive MTC (mMTC)” targeted for large number of low-power deviceconnections such as 1 million per km² with less stringent thereliability, data rate, and latency requirements.

In order for the 5G network to support such diverse services withdifferent quality of services (QoS), one method has been identified in3GPP specification, called network slicing. To utilize PHY resourcesefficiently and multiplex various slices (with different resourceallocation schemes, numerologies, and scheduling strategies) in DL-SCH,a flexible and self-contained frame or subframe design is utilized.

FIG. 9 illustrates an example multiplexing of two slices 900 accordingto embodiments of the present disclosure. The embodiment of themultiplexing of two slices 900 illustrated in FIG. 9 is for illustrationonly. FIG. 9 does not limit the scope of this disclosure to anyparticular implementation of the multiplexing of two slices 900.

Two exemplary instances of multiplexing two slices within a commonsubframe or frame are depicted in FIG. 9 . In these exemplaryembodiments, a slice can be composed of one or two transmissioninstances where one transmission instance includes a control (CTRL)component (e.g., 920 a, 960 a, 960 b, 920 b, or 960 c) and a datacomponent (e.g., 930 a, 970 a, 970 b, 930 b, or 970 c). In embodiment910, the two slices are multiplexed in frequency domain whereas inembodiment 950, the two slices are multiplexed in time domain. These twoslices can be transmitted with different sets of numerology.

3GPP specification supports up to 32 CSI-RS antenna ports which enable agNB to be equipped with a large number of antenna elements (such as 64or 128). In this case, a plurality of antenna elements is mapped ontoone CSI-RS port. For next generation cellular systems such as 5G, themaximum number of CSI-RS ports can either remain the same or increase.

FIG. 10 illustrates an example antenna blocks 1000 according toembodiments of the present disclosure. The embodiment of the antennablocks 1000 illustrated in FIG. 10 is for illustration only. FIG. 10does not limit the scope of this disclosure to any particularimplementation of the antenna blocks 1000.

For mmWave bands, although the number of antenna elements can be largerfor a given form factor, the number of CSI-RS ports—which can correspondto the number of digitally precoded ports—tends to be limited due tohardware constraints (such as the feasibility to install a large numberof ADCs/DACs at mmWave frequencies) as illustrated in FIG. 10 . In thiscase, one CSI-RS port is mapped onto a large number of antenna elementswhich can be controlled by a bank of analog phase shifters. One CSI-RSport can then correspond to one sub-array which produces a narrow analogbeam through analog beamforming. This analog beam can be configured tosweep across a wider range of angles by varying the phase shifter bankacross symbols or subframes. The number of sub-arrays (equal to thenumber of RF chains) is the same as the number of CSI-RS portsN_(CSI-PORT). A digital beamforming unit performs a linear combinationacross N_(CSI-PORT) analog beams to further increase precoding gain.While analog beams are wideband (hence not frequency-selective), digitalprecoding can be varied across frequency sub-bands or resource blocks.

Although exemplary descriptions and embodiments to follow assumeorthogonal frequency division multiplexing (OFDM) or orthogonalfrequency division multiple access (OFDMA), the present disclosure canbe extended to other OFDM-based transmission waveforms or multipleaccess schemes such as filtered OFDM (F-OFDM).

FIG. 11 illustrates an example network configuration 1100 according toembodiments of the present disclosure. The embodiment of the networkconfiguration 1100 illustrated in FIG. 11 is for illustration only. FIG.11 does not limit the scope of this disclosure to any particularimplementation of the configuration 1100.

In order for the 5G network to support such diverse services withdifferent quality of services (QoS), one scheme has been identified in3GPP specification, called network slicing.

As shown in FIG. 11 , An operator's network 1110 includes a number ofradio access network(s) 1120 (RAN(s)) that are associated with networkdevices such as gNBs 1130 a and 1130 b, small cell base stations(femto/pico gNBs or Wi-Fi access points) 1135 a and 1135 b. The network1110 can support various services, each represented as a slice.

In the example, an URLL slice 1140 a serves UEs requiring URLL servicessuch as cars 1145 b, trucks 1145 c, smart watches 1145 a, and smartglasses 1145 d. Two mMTC slices 1150 a and 550 b serve UEs requiringmMTC services such as power meters 555 b, and temperature control box1155 b. One eMBB slice 1160 a serves UEs requiring eMBB services such ascells phones 1165 a, laptops 1165 b, and tablets 1165 c. A deviceconfigured with two slices can also be envisioned.

To enable digital precoding, efficient design of CSI-RS is a crucialfactor. For this reason, three types of CSI reporting mechanismcorresponding to three types of CSI-RS measurement behavior aresupported, for example, “CLASS A” CSI reporting which corresponds tonon-precoded CSI-RS, “CLASS B” reporting with K=1 CSI-RS resource whichcorresponds to UE-specific beamformed CSI-RS, and “CLASS B” reportingwith K>1 CSI-RS resources which corresponds to cell-specific beamformedCSI-RS.

For non-precoded (NP) CSI-RS, a cell-specific one-to-one mapping betweenCSI-RS port and TXRU is utilized. Different CSI-RS ports have the samewide beam width and direction and hence generally cell wide coverage.For beamformed CSI-RS, beamforming operation, either cell-specific orUE-specific, is applied on a non-zero-power (NZP) CSI-RS resource (e.g.,comprising multiple ports). At least at a given time/frequency, CSI-RSports have narrow beam widths and hence not cell wide coverage, and atleast from the gNB perspective. At least some CSI-RS port-resourcecombinations have different beam directions.

In scenarios where DL long-term channel statistics can be measuredthrough UL signals at a serving eNodeB, UE-specific BF CSI-RS can bereadily used. This is typically feasible when UL-DL duplex distance issufficiently small. When this condition does not hold, however, some UEfeedback is necessary for the eNodeB to obtain an estimate of DLlong-term channel statistics (or any of representation thereof). Tofacilitate such a procedure, a first BF CSI-RS transmitted withperiodicity T1 (ms) and a second NP CSI-RS transmitted with periodicityT2 (ms), where T1≤T2. This approach is termed hybrid CSI-RS. Theimplementation of hybrid CSI-RS is largely dependent on the definitionof CSI process and NZP CSI-RS resource.

In the 3GPP LTE specification, MIMO has been identified as an essentialfeature in order to achieve high system throughput requirements and itwill continue to be the same in NR. One of the key components of a MIMOtransmission scheme is the accurate CSI acquisition at the eNB (or TRP).For MU-MIMO, in particular, the availability of accurate CSI isnecessary in order to guarantee high MU performance. For TDD systems,the CSI can be acquired using the SRS transmission relying on thechannel reciprocity. For FDD systems, on the other hand, the CSI can beacquired using the CSI-RS transmission from the eNB, and CSI acquisitionand feedback from the UE. In legacy FDD systems, the CSI feedbackframework is ‘implicit’ in the form of CQI/PMFRI derived from a codebookassuming SU transmission from the eNB. Because of the inherent SUassumption while deriving CSI, this implicit CSI feedback is inadequatefor MU transmission. Since future (e.g., NR) systems are likely to bemore MU-centric, this SU-MU CSI mismatch will be a bottleneck inachieving high MU performance gains. Another issue with implicitfeedback is the scalability with larger number of antenna ports at theeNB. For large number of antenna ports, the codebook design for implicitfeedback is quite complicated, and the designed codebook is notguaranteed to bring justifiable performance benefits in practicaldeployment scenarios (for example, only a small percentage gain can beshown at the most).

In 5G or NR systems, the above-mentioned CSI reporting paradigm from LTEis also supported and referred to as Type I CSI reporting. In additionto Type I, a high-resolution CSI reporting, referred to as Type II CSIreporting, is also supported to provide more accurate CSI information togNB for use cases such as high-order MU-MIMO.

FIG. 12 illustrates an antenna port layout 1200, where N₁ and N₂ are thenumber of antenna ports with the same polarization in the first andsecond dimensions, respectively. For 2D antenna port layouts, N₁>1,N₂>1, and for 1D antenna port layouts N₁>1 and N₂=1. So, for adual-polarized antenna port layout, the total number of antenna ports is2N₁N₂.

As described in U.S. patent application Ser. No. 15/490,561, filed Apr.18, 2017 and entitled “Method and Apparatus for Explicit CSI Reportingin Advanced Wireless Communication Systems,” which is incorporatedherein by reference in its entirety, a UE is configured withhigh-resolution (e.g. Type II) CSI reporting in which the linearcombination based Type II CSI reporting framework is extended to includea frequency dimension in addition to the first and second antenna portdimensions.

FIG. 13 illustrates a 3D grid 1300 of the oversampled DFT beams (1stport dim., 2nd port dim., freq. dim.) in which

1st dimension is associated with the 1st port dimension,

2nd dimension is associated with the 2nd port dimension, and

3rd dimension is associated with the frequency dimension.

The basis sets for 1^(st) and 2^(nd) port domain representation areoversampled DFT codebooks of length-N₁ and length-N₂, respectively, andwith oversampling factors O₁ and O₂, respectively. Likewise, the basisset for frequency domain representation (i.e., 3rd dimension) is anoversampled DFT codebook of length-N₃ and with oversampling factor O₃.In one example, O₁=O₂=O₃=4. In another example, the oversampling factorsO_(i) belongs to {2, 4, 8}. In yet another example, at least one of O₁,O₂, and O₃ is higher layer configured (via RRC signaling).

A UE is configured with higher layer parameter CodebookType set to‘TypeII-Compression’ or ‘TypeIII’ for an enhanced Type II CSI reportingin which the pre-coders for all SBs and for a given layer l=1, . . . ,ν, where ν is the associated RI value, is given by either

$\begin{matrix}{W^{l} = {{{AC}_{l}B^{H}} =}} & \left( {{Eq}.1} \right)\end{matrix}$ $\begin{bmatrix}a_{0} & a_{1} & \ldots & a_{L - 1}\end{bmatrix}\begin{bmatrix}c_{l,0,0} & c_{l,0,1} & \ldots & c_{l,0,{M - 1}} \\c_{l,1,0} & c_{l,1,1} & \ldots & c_{l,1,{M - 1}} \\ \vdots & \vdots & \vdots & \vdots \\c_{l,{L - 1},0} & c_{l,{L - 1},1} & \ldots & c_{l,{L - 1},{M - 1}}\end{bmatrix}$ $\begin{bmatrix}b_{0} & b_{1} & \ldots & b_{M - 1}\end{bmatrix}^{H} =$${{\sum_{m = 0}^{M - 1}{\sum_{i = 0}^{L - 1}{c_{l,i,m}\left( {a_{i}b_{m}^{H}} \right)}}} = {\sum_{i = 0}^{L - 1}{\sum_{m = 0}^{M - 1}{c_{l,i,k}\left( {a_{i}b_{m}^{H}} \right)}}}},$or $\begin{matrix}{W^{l} = {{\begin{bmatrix}A & 0 \\0 & A\end{bmatrix}C_{l}B^{H}} =}} & \left( {{Eq}.2} \right)\end{matrix}$ $\begin{bmatrix}\begin{matrix}a_{0} & a_{1} & \ldots & a_{L - 1}\end{matrix} & 0 \\0 & \begin{matrix}a_{0} & a_{1} & \ldots & a_{L - 1}\end{matrix}\end{bmatrix}$ ${\begin{bmatrix}c_{l,0,0} & c_{l,0,1} & \ldots & c_{l,0,{M - 1}} \\c_{l,1,0} & c_{l,1,1} & \ldots & c_{l,1,{M - 1}} \\ \vdots & \vdots & \vdots & \vdots \\c_{l,{L - 1},0} & c_{l,{L - 1},1} & \ldots & c_{l,{L - 1},{M - 1}}\end{bmatrix}\begin{bmatrix}b_{0} & b_{1} & \ldots & b_{M - 1}\end{bmatrix}}^{H} =$ $\begin{bmatrix}{\sum_{m = 0}^{M - 1}{\sum_{i = 0}^{L - 1}{c_{l,i,m}\left( {a_{i}b_{m}^{H}} \right)}}} \\{\sum_{m = 0}^{M - 1}{\sum_{i = 0}^{L - 1}{c_{l,{i + L},m}\left( {a_{i}b_{m}^{H}} \right)}}}\end{bmatrix},$where

N₁ is a number of antenna ports in a first antenna port dimension,

N₂ is a number of antenna ports in a second antenna port dimension,

N₃ is a number of SBs or frequency domain (FD) units/components for PMIreporting (that comprise the CSI reporting band), which can be different(e.g. less than) from a number of SBs for CQI reporting.

a_(i) is a 2N₁N₂×1 (Eq. 1) or N₁N₂×1 (Eq. 2) column vector,

b_(k) is a N₃×1 column vector,

c_(i,i,k) is a complex coefficient.

In a variation, when a subset K<2LM coefficients (where K is eitherfixed, configured by the gNB or reported by the UE), then thecoefficient c_(l,i,m) in precoder equations Eq. 1 or Eq. 2 is replacedwith ν_(l,i,k)×c_(l,i,m), where

ν_(l,i,m)=1 if the coefficient c_(l,i,m) is reported by the UE accordingto some embodiments of this disclosure.

ν_(l,i,m)=0 otherwise (i.e., c_(l,i,m) is not reported by the UE).

The indication whether ν_(l,i,m)=1 or 0 is according to some embodimentsof this disclosure.

In a variation, the precoder equations Eq. 1 or Eq. 2 are respectivelygeneralized to

$\begin{matrix}{W^{l} = {\sum_{i = 0}^{L - 1}{\sum_{m = 0}^{M_{i} - 1}{c_{l,i,m}\left( {a_{i}b_{i,m}^{H}} \right)}}}} & \left( {{Eq}.3} \right)\end{matrix}$ and $\begin{matrix}{{W^{l} = \begin{bmatrix}{\sum_{i = 0}^{L - 1}{\sum_{m = 0}^{M_{i} - 1}{c_{l,i,m}\left( {a_{i}b_{i,m}^{H}} \right)}}} \\{\sum_{i = 0}^{L - 1}{\sum_{m = 0}^{M_{i} - 1}{c_{l,{i + L},m}\left( {a_{i}b_{i,m}^{H}} \right)}}}\end{bmatrix}},} & \left( {{Eq}.4} \right)\end{matrix}$where for a given i, the number of basis vectors is M_(i) and thecorresponding basis vectors are {b_(i,m)}. Note that M_(i) is the numberof coefficients c_(l,i,m) reported by the UE for a given i, whereM_(i)≤M (where {M_(i)} or ΣM_(i) is either fixed, configured by the gNBor reported by the UE).

The columns of W^(l) are normalized to norm one. For rank R or R layers(ν=R), the pre-coding matrix is given by

$W^{(R)} = {{\frac{1}{\sqrt{R}}\begin{bmatrix}W^{1} & W^{2} & \ldots & W^{R}\end{bmatrix}}.}$Eq. 2 is assumed in the rest of the disclosure. The embodiments of thedisclosure, however, are general and are also applicable to Eq. 1, Eq. 3and Eq. 4.

Here L≤2N₁N₂ and K≤N₃. If L=2N₁N₂, then A is an identity matrix, andhence not reported. Likewise, if K=N₃, then B is an identity matrix, andhence not reported. Assuming L<2N₁N₂, in an example, to report columnsof A, the oversampled DFT codebook is used. For instance, a_(i)=ν_(l,m),where the quantity v_(l,m) is given by:

u m = { [ 1 e j ⁢ 2 ⁢ π ⁢ m O 2 ⁢ N 2 … j ⁢ 2 ⁢ π ⁢ m ⁡ ( N 2 - 1 ) O 2 ⁢ N 2 ] N2 > 1 1 N 2 = 1 . v l , m = [ u m e j ⁢ 2 ⁢ π ⁢ l O 1 ⁢ N 1 ⁢ u m … j ⁢ 2 ⁢ π ⁢l ⁡ ( N 1 - 1 ) O 1 ⁢ N 1 u m ] T

Similarly, assuming K<N₃, in an example, to report columns of B, theoversampled DFT codebook is used. For instance, b_(k)=w_(k), where thequantity w_(k) is given by:

w k = [ 1 e j ⁢ 2 ⁢ π ⁢ k O 3 ⁢ N 3 … j ⁢ 2 ⁢ π ⁢ k ⁡ ( N 3 - 1 ) O 3 ⁢ N 3 ] .

In another example, discrete cosine transform DCT basis is used toconstruct/report basis B for the 3^(rd) dimension. The m-th column ofthe DCT compression matrix is simply given by

$\left\lbrack W_{f} \right\rbrack_{nm} = \left\{ {\begin{matrix}{\frac{1}{\sqrt{K}},{n = 0}} \\{{\sqrt{\frac{2}{K}}\cos\frac{{\pi\left( {{2m} + 1} \right)}n}{2K}},{n = 1},{{\ldots K} - 1}}\end{matrix},,{{{and}K} = N_{3}},{{{and}m} = 0},\ldots,{N_{3} - 1.}} \right.$

Since DCT is applied to real valued coefficients, the DCT is applied tothe real and imaginary components (of the channel or channeleigenvectors) separately. Alternatively, the DCT is applied to themagnitude and phase components (of the channel or channel eigenvectors)separately. The use of DFT or DCT basis is for illustration purposeonly. The disclosure is applicable to any other basis vectors toconstruct/report A and B.

Also, in an alternative, for reciprocity-based Type II CSI reporting, aUE is configured with higher layer parameter CodebookType set to‘TypeII- PortSelection-Compression’ or ‘TypeIII-PortSelection’ for anenhanced Type II CSI reporting with port selection in which thepre-coders for all SBs and for a given layer l=1, . . . , ν, where ν isthe associated RI value, is given by W^(l)=AC_(l)B^(H), where N₁, N₂,N₃, and c_(l,i,k) are defined as above except that the matrix Acomprises port selection vectors. For instance, the L antenna ports perpolarization or column vectors of A are selected by the index q_(l),where

$q_{1} \in \left\{ {0,1,{{\ldots\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil} - 1}} \right\}$(this requires

$\left\lceil {\log_{2}\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil} \right\rceil$bits), and the value of d is configured with the higher layer parameterPortSelectionSamplingSize, where

$d \in {{\left\{ {1,2,3,4} \right\}{and}d} \leq {{\min\left( {\frac{P_{{CSI} - {RS}}}{2},\ L} \right)}.}}$To report columns of A, the port selection vectors are used, Forinstance, a_(i)=ν_(m), where the quantity ν_(m) is aP_(CSI-RS)/2-element column vector containing a value of 1 in element (mmod P_(CSI-RS)/2) and zeros elsewhere (where the first element iselement 0).

On a high level, a precoder W^(l) can be described as follows.W=AC _(l) B ^(H) =W ₁ {tilde over (W)} ₂ W _(f) ^(H),where A=W₁ corresponds to the W₁ in Type II CSI codebook, and B=W_(f).The C={tilde over (W)}₂ matrix includes all the required linearcombination coefficients (e.g. amplitude and phase or real orimaginary).

This disclosure proposes a few embodiments about (1) N3 and (2)precoders comprising multiple segments (groupings) in either spatialdomain (SD) or frequency domain (FD) or both.

In one embodiment 1A, N3 is unrestricted and can take all possiblevalues. For example, if a number of SBs for PMI reporting T=R×S whereS=N_(SB)=number of SBs for CQI reporting belonging to {3,4, . . . ,19},where R≥1, then N3 can take any value from {3R, 4R, . . . ,19R}. In oneexample, R=1 or 2.

In one embodiment 1B, N3 is restricted and takes a value that satisfiesa certain condition. A few examples of the certain condition are asfollows.

In one example, the certain condition corresponds to the following:

-   -   N₃=the smallest candidate value for N3 such that N₃≥T.

In another example, the certain condition corresponds to the following:

-   -   N₃=the smallest candidate value for N3 such that N₃≥T.    -   The last (N₃−T+1 though N₃) T columns of the precoder W^(l)        correspond to the precoders for T SBs or FD units for which the        UE is configured to report the PMIs, and the remaining (1        through N₃−T) columns of the precoder W^(l) are either ignored        or correspond to the precoders for N₃−T SBs (for PMI reporting)        that come before the (N₃−T+1)-th SB, e.g. 1, 2, . . . , N₃−T.

In another example, the certain condition corresponds to the following:

-   -   N₃=the smallest candidate value for N3 such that N₃≥T.    -   The first (1 though T) T columns of the precoder W^(l)        correspond to the precoders for T SBs or FD units for which the        UE is configured to report the PMIs, and the remaining (T+1        through N₃) columns of the precoder W^(l) are either ignored or        correspond to the precoders for N₃−T SBs (for PMI reporting)        that come after the T-th SB, e.g. T+1, T+2, . . . , N3.

In another example, the certain condition corresponds to the following:

-   -   N₃=the smallest candidate value for N3 such that N₃≥T.    -   The (x₁+1 through N₃−x₂=x₁+T) T columns of the precoder W^(l)        correspond to the precoders for T SBs or FD units for which the        UE is configured to report the PMIs, x₁ of the remaining (1        through x₁) columns of the precoder W^(l) are either ignored or        correspond to the precoders for x₁ SBs (for PMI reporting) that        come before the (x₁+1)-th SB, e.g. 1, 2, . . . , x₁, and x₂ of        the remaining (T+x₁+1 through N₃) x₂ columns of the precoder        W^(l) are either ignored or correspond to the precoders for x₂        SBs (for PMI reporting) that come after the (T+x₁)-th SB, e.g.        T+x₁+1, T+x₁+2, . . . , N₃.        Where

${x_{1} = {{\left\lceil \frac{\left( {N_{3} - T} \right)}{2} \right\rceil{and}x_{2}} = {{N_{3} - T - \left\lceil \frac{\left( {N_{3} - T} \right)}{2} \right\rceil} = {N_{3} - T - x_{1}}}}},{{{or}x_{1}} = {{\left\lfloor \frac{\left( {N_{3} - T} \right)}{2} \right\rfloor{and}x_{2}} = {{N_{3} - T - \left\lfloor \frac{\left( {N_{3} - T} \right)}{2} \right\rfloor} = {N_{3} - T - x_{1}}}}},{{{or}x_{2}} = {{\left\lceil \frac{\left( {N_{3} - T} \right)}{2} \right\rceil{and}x_{1}} = {{N_{3} - T - \left\lceil \frac{\left( {N_{3} - T} \right)}{2} \right\rceil} = {N_{3} - T - x_{2}}}}},{{{or}x_{2}} = {{\left\lfloor \frac{\left( {N_{3} - T} \right)}{2} \right\rfloor{and}x_{1}} = {{N_{3} - T - \left\lfloor \frac{\left( {N_{3} - T} \right)}{2} \right\rfloor} = {N_{3} - T - {x_{2}.}}}}}$

At least one of the following alternatives is used for the candidate N₃value.

In one alternative Alt 1B-0, N3 is a multiple of 2, i.e., N3 belongs to{2, 4, 8, 16, 32, . . . }. At least one of the following examples isused.

In one example Ex 1B-0-0 (R=1): if the number of SBs for PMI reportingT=S, where S=the number of SBs for CQI reporting belonging to {3,4, . .. ,19}, then N₃∈{4,8,16,32}.

In one example Ex 1B-0-1 (R=2): if the number of SBs for PMI reportingT=R×S=2S, where S=the number of SBs for CQI reporting belonging to {6,8,. . . ,38}, then N₃∈{8,16,32,64}.

In one alternative Alt 1B-1, N3 is a multiple of 2 or 3, i.e., N3belongs to {2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 27, 32, 36, . . . }. Atleast one of the following examples is used.

In one example Ex1B-1-0 (R=1): if number of SBs for PMI reporting T=S,where S=number of SBs for CQI reporting belonging to {3,4, . . . ,19},then N₃∈{3,4,6,8,9,12,16,18,24}.

In one example Ex1B-1-1 (R=2): if number of SBs for PMI reportingT=R×S=2S, where S=number of SBs for CQI reporting belonging to {6,8, . .. ,38}, then N₃∈{6,8,9,12,16,18,24,27,32,36,48}.

In one alternative Alt 1B-2, N3 is a multiple of 2 or 3 or 5, i.e., N3belongs to {2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 24, 25, 27, 30,32, . . . }. At least one of the following examples is used.

In one example Ex1B-2-0 (R=1): if number of SBs for PMI reporting T=S,where S=number of SBs for CQI reporting belonging to {3,4, . . . ,19},then N₃∈{3,4,5,6,8,9,10,12,15,16,18,20}.

Ex1B-2-1 (R=2): if number of SBs for PMI reporting T=R×S=2S, whereS=number of SBs for CQI reporting belonging to {6,8, . . . ,38}, thenN₃∈{6,8,9,10,12,15,16,18,20,24,25,27,30,32,36,40}.

In one embodiment 1C, N3 is configured (e.g., via higher layer RRCsignaling). The set of candidate values for N3 is according to one ofexamples in embodiment 1A/1B, and is either fixed, or optionally, higherlayer configured.

In one embodiment 1D, the value N3 is determined based on a condition onT=N_(SB)×R=S×R such that:

N₃ is according to Alt 1A if T≤α, and

N₃ is according to one of the alternatives or examples in Alt 1B if T>α,where α is a fixed number. In one example, α is a prime number, e.g.,α=13 or 17 or 19. In one example of this embodiment, α=13, and

N₃ is according to Alt 1A, i.e., N₃=T=N_(SB)×R if T≤13, and

N₃ is according to Alt 1B-2 if T>13, i.e., N₃ is a multiple of 2 or 3 or5 such that N₃≥T.

In one embodiment 1E, the value N3 is determined based on a condition onT=N_(SB)×R=S×R such that:

N₃ is according to Alt 1A if T≤α, and

N₃ is according to one of the alternatives or examples in Alt 1B if T>α.In addition,

N₃ is segmented into two segments as proposed later in embodiments2A/2B/2C, where α is a fixed number. In one example, α is a primenumber, e.g., α=13 or 17 or 19. In one example of this embodiment, α=13,and

N₃ is according to Alt 1A, i.e., N₃=T=N_(SB)×R if T≤13, and

N₃ is according to Alt 1B-2 if T>13, i.e., N₃ is a multiple of 2 or 3 or5 such that N₃≥T. In addition, N₃ is segmented into two segmentscomprising (N_(3,0), N_(3,1)) FD components as proposed later inembodiments 2A/2B/2C. An example of N₃ values and (N_(3,0), N_(3,1))values in shown in Table 1. For some N₃ values, there are multiple(N_(3,0), N_(3,1)) values shown in the table as examples. Either onlyone of them will be used or one of them configured or reported by theUE.

TABLE 1 Example candidate values for (N_(3, 0), N_(3, 1)) when T > 13 T= N_(SB) × R N₃ (N_(3, 0), N_(3, 1)) R = 1 14 15 (8, 7), (9, 6), (6, 9)15 15 16 16 (8, 8) 17 18 (9, 9) 18 18 19 20 (10, 10) R = 2 20 20 22 24(12, 12) 24 24 26 27 (15, 12), (12, 15) 28 30 (15, 15) 30 30 32 32 (16,16) 34 36 (18, 18) 36 36 38 40 (20, 18), (18, 20)

In one embodiment 1F, the value N3 is determined exactly that same wayas in embodiment 1E except that the solution when T>13 is replaced withthe following. The N₃ value is a multiple of 2 or 3 or 5 such that N₃≤T.In addition, N₃ is segmented into two segments comprising (N_(3,0),N_(3,1)) FD components as proposed later in embodiments 2A/2B/2C. Anexample of N₃ values and (N_(3,0), N_(3,1)) values in shown in Table 2.For some N₃ values, there are multiple (N_(3,0), N_(3,1)) values shownin the table as examples. Either only one of them will be used or one ofthem configured or reported by the UE.

TABLE 2 Example candidate values for (N_(3, 0), N_(3, 1)) when T > 13 T= N_(SB) × R N₃ (N_(3, 0), N_(3, 1)) R = 1 14 12 (6, 6) 15 15 (8, 7),(9, 6), (6, 9) 16 16 (8, 8) 17 16 18 18 (9, 9) 19 18 R = 2 20 20 (10,10) 22 20 24 24 (12, 12) 26 25 (13, 12), (10, 15), (15, 10) 28 27 (15,12), (12, 15) 30 30 (15, 15) 32 32 (16, 16) 34 32 36 36 (18, 18) 38 36

In embodiment 1G, a UE reports via UE capability signaling that whetherit can support all values of N3 (i.e., N3 is unrestricted according toAlt 1A) or only a subset of N3 values (i.e., N3 is restricted accordingto Alt1B). If the UE supports only a restricted subset of N3 values,then the restricted subset is determined according to at least one ofthe embodiments 1B, 1C, 1D, or, 1E, or alternatives or examples therein.

In one variation, if the UE supports only a restricted subset of N3values, then the UE reports the restricted set of N3 values that itsupports (e.g., via UE capability signaling).

In another variation, if the UE supports only a restricted subset of N3values, then the restricted set of N3 values is fixed (e.g., Alt 1B-2 orembodiment 1D or embodiment 1E).

In another variation, if the UE supports only a restricted subset of N3values, then the UE reports a set of N3 values that it cannot support(e.g., via UE capability signaling). The restricted subset of N3 valuesthat the UE supports corresponds to the set of all N3 values excludingthe set of N3 values that the UE cannot support.

In another variation, if the UE supports only a restricted subset of N3values, then a set of N3 values that the UE cannot support is fixed. Therestricted subset of N3 values that the UE supports corresponds to theset of all N3 values excluding the set of N3 values that the UE cannotsupport.

In one example, if the restricted set of N3 values is according to Alt1B-2 (i.e., N3 is a multiple of 2 or 3 or 5), then

For R=1,

-   -   if the number of SBs for PMI reporting T=S, where S=number of        SBs for CQI reporting belonging to {3,4, . . . ,19}; and the UE        reports that it can support all values of N3, then N₃=T=S∈{3,4,        . . . ,19}, and    -   if the number of SBs for PMI reporting T=S, where S=number of        SBs for CQI reporting belonging to {3,4, . . . ,19}; and the UE        reports that it can support only a subset of N3 values, then        N₃∈{3,4,5,6,8,9,10,12,15,16,18,20}.

For R=2,

-   -   if the number of SBs for PMI reporting T=R×S=2S, where S=number        of SBs for CQI reporting belonging to {6,8, . . . ,38}; and the        UE reports that it can support all values of N3, then        N₃=T=2S∈{6,8, . . . ,38}, and    -   if number of SBs for PMI reporting T=R×S=2S, where S=number of        SBs for CQI reporting belonging to {6,8, . . . ,38}; and the UE        reports that it can support only a sub set of N3 values, then        N₃∈{6,8,9,10,12,15,16,18,20,24,25,27,30,32,36,40}.

In one embodiment 2A, the number of FD compression units, or, the numberof SBs for PMI reporting (i.e. length N₃ of FD basis vectors b_(m) inEq. 2) is divided (segmented or grouped) into multiple segments, and theproposed framework for compression in SD and FD is extended for thissegmentation (grouping) of SBs in FD. At least one of the followingalternatives is used for number of segments.

In one alternative Alt 2A-1, the number of segments (groups) is fixed,e.g. to 2.

In one alternative Alt 2A-2, the number of segments (groups) isconfigured (e.g. via higher layer signaling).

In one alternative Alt 2A-3, the number of segments (groups) is reportedby the UE. For example, if two-part UCI is used reported CSI, thennumber of segments is reported in UCI part 1. In another example, it isreported as part of the WB CSI component in UCI part 2.

In one alternative Alt 2A-4, the number of segments (groups) is one bydefault. But, the number of segments greater than 1 (e.g. 2) can beconfigured (turned ON) via higher layer signaling.

Let P be the number of segments. Then, a precoder W^(l) can be describedas follows:W=AC _(l) B ^(H) =W ₁ {tilde over (W)} ₂ W _(f) ^(H)

W₁=A is according to one of Eq. 1 through 4.

$W_{f} = \begin{bmatrix}W_{f,0} & 0 & & \ldots & 0 \\0 & W_{f,1} & & \ldots & 0 \\ \vdots & \vdots & \ddots & & \vdots \\0 & 0 & \cdots & & W_{f,{P - 1}}\end{bmatrix}$where W_(f,p) for p∈{0,1, . . . ,P−1} is FD basis for segment p, and issize M_(p)×N_(3,p); M_(p) is number of FD basis vectors for segment pand N_(3,p) is dimension (size) of FD basis vectors comprising columnsof W_(f,p).

C_(l)=[C_(l,0) C_(l,1) . . . C_(l,P−1)] where c_(l,p) for p∈{0,1, . . .,P−1} is coefficient matrix segment p, and is size 2L×M_(p).

The set of values {M_(p)} is according to one of the following.

In one alternative Alt 2A-5: M_(p)=M/P for all p assuming P divides M.If P does not divide M, then M_(p)=

M/P

for all p∈{0,1, . . . ,P−2} and M_(p)=M−(P−1)

M/P

for p=P−1.

In one alternative Alt 2A-6: {M_(p)} is configured.

In one alternative Alt 2A-7: {M_(p)} is reported by the UE, but theirsum ΣM_(p) is configured.

The set of values {N_(3,p)} is according to one of the following.

In one alternative Alt 2A-8: N_(3,p)=N₃/P for all p assuming P dividesN3. If P does not divide N₃, then N_(3,p)=

N₃/P

for all p∈{0,1, . . . ,P−2} and N_(3,p)=N₃−(P−1)

N₃/P

for p=P−1.

In one alternative Alt 2A-9: {N_(3,p)} is configured.

In one alternative Alt 2A-10: {N_(3,p)} is reported by the UE, but theirsum N₃=ΣN_(3,p) is configured.

In one variation, the segmentation is considered regardless of whetherSBs for PMI reporting are contiguous or not. In another variation, thesegmentation is considered only when SBs for PMI reporting arenon-contiguous, i.e., the number of segments=1 for contiguous SBs and >1(e.g., 2) for non-contiguous SBs. In yet another variation, thesegmentation is considered when SBs for PMI reporting arenon-contiguous, i.e., the number of segments >1 (e.g., 2) fornon-contiguous SBs, and whether or not segmentation is used forcontiguous SBs is configurable.

If the number of segments is 2 (P=2), then Eq. (1) for precoder can beextended as follows.

$\begin{matrix}\begin{matrix}{W^{l} = {{W_{1}{\overset{\sim}{W}}_{2}W_{f}^{H}} = {{{AC}_{l}B^{H}} = {A\left\lbrack {\begin{matrix}C_{l,0} & {\left. C_{l,1} \right\rbrack\begin{bmatrix}B_{0} & 0 \\0 & B_{1}\end{bmatrix}}^{H}\end{matrix} =} \right.}}}} \\{{{\left\lbrack {a_{0}a_{1}\ldots a_{L - 1}} \right\rbrack\left\lbrack {c_{l,0}c_{l,1}} \right\rbrack}\begin{bmatrix}{b_{0,0}b_{0,1}\ldots b_{0,{M_{0} - 1}}} & 0 \\0 & {b_{1,0}b_{1,1}\ldots b_{1,{M_{1} - 1}}}\end{bmatrix}^{H}} =} \\{{{\overset{L - 1}{\sum\limits_{i = 0}}{a_{i}\left\lbrack {\overset{M_{0} - 1}{\sum\limits_{m = 0}}{c_{l,0,i,m}b_{0,m}^{H}{\overset{M_{1} - 1}{\sum\limits_{m = 0}}{c_{l,1,i,m}b_{1,m}^{H}}}}} \right\rbrack}} = \left\lbrack {\overset{L - 1}{\sum\limits_{i = 0}}{\overset{M_{0} - 1}{\sum\limits_{m = 0}}{{c_{l,0,i,m}\left( {a_{i}b_{0,m}^{H}} \right)}{\overset{L - 1}{\sum\limits_{i = 0}}{\overset{M_{1} - 1}{\sum\limits_{m = 0}}{c_{l,1,i,m}\left( {a_{i}b_{1,m}^{H}} \right)}}}}}} \right\rbrack},}\end{matrix} & \left( {{Eq}.5} \right)\end{matrix}$

Likewise, Eq. (2) can be extended as follows.

$\begin{matrix}\begin{matrix}{W^{l} = {{W_{1}{\overset{\sim}{W}}_{2}W_{f}^{H}} = {\begin{bmatrix}A & 0 \\0 & A\end{bmatrix}\left\lbrack \text{⁠}{{\begin{matrix}C_{l,0} & \left. C_{l,1} \right\rbrack\end{matrix}\begin{bmatrix}B_{0} & 0 \\0 & B_{1}\end{bmatrix}}^{H} =} \right.}}} \\{\begin{bmatrix}{a_{0}a_{1}\ldots a_{L - 1}} & 0 \\0 & {a_{0}a_{1}\ldots a_{L - 1}}\end{bmatrix}\left\lbrack {{\begin{matrix}C_{l,0} & \left. C_{l,1} \right\rbrack\end{matrix}\begin{bmatrix}{b_{0,0}b_{0,1}\ldots b_{0,{M_{0} - 1}}} & 0 \\0 & {b_{1,0}b_{1,1}\ldots b_{1,{M_{1} - 1}}}\end{bmatrix}}^{H} =} \right.} \\{{\begin{bmatrix}{\overset{L - 1}{\sum\limits_{i = 0}}{a_{i}\left\lbrack {\overset{M_{0} - 1}{\sum\limits_{m = 0}}{c_{l,0,i,m}b_{0,m}^{H}}} \right.}} & \left. {\overset{M_{1} - 1}{\sum\limits_{m = 0}}{c_{l,1,i,m}b_{1,m}^{H}}} \right\rbrack \\{\overset{L - 1}{\sum\limits_{i = 0}}{a_{i}\left\lbrack {\overset{M_{0} - 1}{\sum\limits_{m = 0}}{c_{l,0,{i + L},m}b_{0,m}^{H}}} \right.}} & \left. {\overset{M_{1} - 1}{\sum\limits_{m = 0}}{c_{l,1,{i + L},m}b_{1,m}^{H}}} \right\rbrack\end{bmatrix} = \left\lbrack \text{⁠}\begin{matrix}{\overset{L - 1}{\sum\limits_{i = 0}}{\overset{M_{0} - 1}{\sum\limits_{m = 0}}{c_{l,0,i,m}\left( {a_{i}b_{0,m}^{H}} \right)}}} & {\overset{L - 1}{\sum\limits_{i = 0}}{\overset{M_{1} - 1}{\sum\limits_{m = 0}}{c_{l,1,i,m}\left( {a_{i}b_{1,m}^{H}} \right)}}} \\{\overset{L - 1}{\sum\limits_{i = 0}}{\overset{M_{0} - 1}{\sum\limits_{m = 0}}{c_{l,0,i,{+ L},m}\left( {a_{i}b_{0,m}^{H}} \right)}}} & {\overset{L - 1}{\sum\limits_{i = 0}}{\overset{M_{1} - 1}{\sum\limits_{m = 0}}{c_{l,1,i,{+ L},m}\left( {a_{i}b_{1,m}^{H}} \right)}}}\end{matrix} \right\rbrack},}\end{matrix} & \left( {{Eq}.6} \right)\end{matrix}$

In one embodiment 2C, to quantize C_(l), the following components arereported.

Strongest coefficient: The index of the strongest coefficient isreported. The value of the strongest coefficient equals 1.

Instead of reporting all coefficients, a subset comprising K₀coefficients is reported. The coefficients not reported equals zero.

The amplitude and phase for each of the reported K₀ coefficients arereported.

At least one of the following alternatives is used to quantizecoefficients.

In one alternative Alt 2C-1: all components are jointly reported (acrossall segments). In particular, A single strongest coefficient is reportedout of all of 2LM coefficients comprising P segments.

The size-K₀ subset is reported out of all of 2LM coefficients comprisingP segments.

The amplitude and phase for each of the reported K₀ coefficients arereported.

In one alternative Alt 2C-2: all components are independently reportedfor each segment. In particular, for each segment p,

A single strongest coefficient is reported out of all of 2LM_(p)coefficients.

The size-K_(0,p) subset is reported out of all of 2LM_(p) coefficients.The amplitude and phase for each of the reported K_(0,p) coefficientsare reported.

In one alternative Alt 2C-3: Some components are jointly reported andthe remaining are independently reported. For example,

The strongest coefficient is reported jointly for all segments.

The size-K₀ subset is reported independently for each segment.

The set of values {K_(0,p)} is according to one of the following.

In one alternative Alt 2C-4: K_(0,p)=K₀/P for all p assuming P dividesK0. If P does not divide K₀, then K_(0,p)=

K₀/P

for all p∈{0,1, . . . ,P−2} and K_(0,p)=K₀−(P−1)

K₀/P

for p=P−1

In one alternative Alt 2C-5: {K_(0,p)} is configured.

In one alternative Alt 2C-6: {K_(0,p)} is reported by the UE, but theirsum K₀=ΣK_(0,p) is configured.

When two-part UCI is used to report CSI, and number of non-zerocoefficient (K₁) is reported in UCI part 1, then a single joint K₁ isreported if Alt 2C-1 is used, and K_(1,p), for each segment p,indicating number of non-zero coefficients in segment p is reported ifAlt 2C-2 is used.

In one embodiment 3A, the number of SD compression units, or, the numberof ports (i.e., length 2N₁N₂ of SD basis vectors a_(i) in Eq. 2) isdivided (segmented or grouped) into multiple segments, and the proposedframework for compression in SD and FD is extended for this segmentation(grouping) of ports in SD. It is straightforward for the skilled in theart to extend the embodiment 2A/2B/2C in this case.

In one example Ex 3A-1, the number of segments in SD is 2, one each forthe two antenna polarizations. In Ex 3A-2, the number of segments in SDis 4, two each for the two antenna polarizations.

In one embodiment 4A, both the number of SD compression units, or, thenumber of ports (i.e., length 2N₁N₂ of SD basis vectors a_(i) in Eq. 2)and the number of FD compression units, or, the number of SBs for PMIreporting (i.e., length N₃ of FD basis vectors b_(m) in Eq. 2) aredivided (segmented or grouped) into multiple segments, and the proposedframework for compression in SD and FD is extended for this segmentation(grouping) of ports in SD. It is straightforward for those skilled inthe art to extend the embodiment 2A/2B/2C/3A in this case.

As described above, on a high level, a precoder W^(l) can be describedas follows.W=AC _(l) B ^(H) =W ₁ {tilde over (W)} ₂ W _(f) ^(H),where A=W₁ corresponds to the W₁ in Type II CSI codebook, and B=W_(f).The C={tilde over (W)}₂ matrix includes all the required linearcombination coefficients (e.g. amplitude and phase or real orimaginary).

Each reported coefficient (c_(l,i,m)=p_(l,i,m)ϕ_(l,i,m)) in {tilde over(W)}₂ is quantized as amplitude coefficient (p_(l,i,m)) and phasecoefficient (ϕ_(l,i,m)). In one example, the amplitude coefficient(p_(l,i,m)) is reported using an A-bit amplitude codebook where Abelongs to {2, 3, 4}. If multiple values for A are supported, then onevalue is configured via higher layer signaling. In another example, theamplitude coefficient (p_(l,i,m)) is reported as p_(l,i,m)=p_(l,i,m)⁽¹⁾p_(l,i,m) ⁽²⁾ where

p_(l,i,m) ⁽¹⁾ is a reference or first amplitude which is reported usinga A1-bit amplitude codebook where A1 belongs to {2, 3, 4}, and

p_(l,i,m) ⁽²⁾ is a differential or second amplitude which is reportedusing a A2-bit amplitude codebook where A2≤A1 belongs to {2, 3, 4}.

For layer l, let us denote the linear combination (LC) coefficientassociated with spatial domain (SD) basis vector (or beam) i∈{0,1, . . .,2L−1} and frequency domain (FD) basis vector (or beam) m∈{0,1, . . .,M−1} as c_(l,i,m), and the strongest coefficient as c_(l,i*,m*). Thestrongest coefficient is reported out of the K_(NZ) non-zero (NZ)coefficients that is reported using a bitmap, where K_(NZ)≤K₀=

β×2LM

<2LM and β is higher layer configured. The remaining 2LM−K_(NZ)coefficients that are not reported by the UE are assumed to be zero. Atleast one of the following quantization schemes is used toquantize/report the K_(NZ) NZ coefficients.

Scheme 0: UE reports the following for the quantization of the NZcoefficients in {tilde over (W)}₂ A

log₂ K_(NZ)

-bit indicator for the strongest coefficient index (i*, m*)

-   -   Strongest coefficient c_(l,i*,m*)=1 (hence its amplitude/phase        are not reported) For {c_(l,i,m), (i, m)≠(i*, m*)}, quantized to        3-bit amplitude, and either 8PSK (3-bit) or 16PSK (4-bit) phase        (which is configurable).    -   For the 3-bit amplitude, a 3-bit amplitude alphabet is used.

Scheme 1: UE reports the following for the quantization of the NZcoefficients in {tilde over (W)}₂ A

log₂ K_(NZ)

-bit indicator for the strongest coefficient index (i*, m*)

-   -   Strongest coefficient c_(l,i*,m*)=1 (hence its amplitude/phase        are not reported)

Two antenna polarization-specific reference amplitudes:

-   -   For the polarization associated with the strongest coefficient        c_(l,i*m*)=1, since the reference amplitude p_(l,i,m) ⁽¹⁾=1, it        is not reported    -   For the other polarization, reference amplitude p_(l,i,m) ⁽¹⁾ is        quantized to 4 bits        -   The 4-bit amplitude alphabet is

$\left\{ {1,\left( \frac{1}{2} \right)^{\frac{1}{4}},\left( \frac{1}{4} \right)^{\frac{1}{4}},\left( \frac{1}{8} \right)^{\frac{1}{4}},\ldots,\left( \frac{1}{2^{14}} \right)^{\frac{1}{4}},0} \right\}.$

For {c_(l,i,m), (i, m)≠(i*, m*)}:

For each polarization, differential amplitudes p_(l,i,m) ⁽²⁾ of thecoefficients calculated relative to the associated polarization-specificreference amplitude and quantized to 3 bits

-   -   The 3-bit amplitude alphabet is

$\left\{ {1,\frac{1}{\sqrt{2}},\frac{1}{2},\frac{1}{2\sqrt{2}},\frac{1}{4},\frac{1}{4\sqrt{2}},\frac{1}{8},\frac{1}{8\sqrt{2}}} \right\}.$

-   -   Note: The final quantized amplitude p_(l,i,m) is given by        p_(l,i,m) ⁽¹⁾×p_(l,i,m) ⁽²⁾

Each phase is quantized to either 8PSK (3-bit) or 16PSK (4-bit) (whichis configurable).

Scheme 2: UE reports the following for the quantization of the NZcoefficients in {tilde over (W)}₂ A

log₂ K_(NZ)

-bit indicator for the strongest coefficient index (i*, m*)

-   -   Strongest coefficient c_(l,i*,m*)=1 (hence its amplitude/phase        are not reported)

For {c_(l,i,m*), i≠i*}: quantized to 4-bit amplitude, and 16PSK phase

-   -   The 4-bit amplitude alphabet is

$\left\{ {1,\left( \frac{1}{2} \right)^{\frac{1}{4}},\left( \frac{1}{4} \right)^{\frac{1}{4}},\left( \frac{1}{8} \right)^{\frac{1}{4}},\ldots,\left( \frac{1}{2^{14}} \right)^{\frac{1}{4}},0} \right\}.$

For {c_(l,i,m), m≠m*}: quantized to 3-bit amplitude, and either 8PSK or16PSK phase (which is configurable)

The 3-bit amplitude alphabet is

$\left\{ {1,\frac{1}{\sqrt{2}},\frac{1}{2},\frac{1}{2\sqrt{2}},\frac{1}{4},\frac{1}{4\sqrt{2}},\frac{1}{8},\frac{1}{8\sqrt{2}}} \right\}.$

In the rest of the disclosure, the details about the high rank (rank>1)extension of the above-mentioned quantization schemes are proposed,where rank corresponds to a number of layers ν (or RI value) that thereported CSI corresponds to. In this disclosure, ν layers are indexed asl=0, 1, 2, . . . ,ν−1.

In the rest the disclosure, it is assumed that K_(NZ) is reported viapart 1 of a two-part UCI comprising UCI part 1 and UCI part 2.

In one embodiment 0, the strongest coefficient c_(l,i*,m*) for rank >1,e.g. RI∈{2,3,4}, is determined/reported using a strongest coefficientindicator (SCI) according to at least one of the following alternatives(Alt). If multiple alternatives are supported, then at least one of thesupported alternatives is either configured (e.g. via higher layer RRCsignaling) or reported by the UE.

In one alternative Alt 0-0: A single strongest coefficient c_(l*,i*,m*)is determined/reported across all layers (i.e., regardless of the υ orRI value) where l* is the index of the layer to which the strongestcoefficient belongs to. For layer l=l*, the index of the strongestcoefficient c_(l*,i*,m*)=1 is reported (hence its amplitude and phaseare not reported), and for layers l≠l*, the strongest coefficientc_(l,i*,m*) is not reported (hence, amplitude and phase are reported forall NZ coefficients for those layers). The number of bits to report thestrongest coefficient is

log₂ ν

+

log₂ K_(NZ,l*)

where

log₂ ν

bits are used to indicate the layer index l*, and

log₂ K_(NZ,l*)

bits are used to indicate the index of the strongest coefficientc_(l*,i*,m*), and K_(NZ,l*) is the number of NZ coefficients reportedfor layer l*. In one alternative, K_(NZ,l*)=aK₀ where K₀=

β×2LM

<2LM and β is higher layer configured, and a is a fixed integer (e.g.a=1 or 2).

In one alternative Alt 0-1: A single strongest coefficient c_(l,i*,m*) sdetermined/reported across all layers (i.e., regardless of the ν or RIvalue). The strongest coefficient c_(l,i*,m*) is common for all layers,i.e., index (i*, m*) of the strongest coefficient is the same for alllayers, which implies that c_(l,i*,m*)=1 for all l=0,1, . . . ,ν−1. Thenumber of bits to report the strongest coefficient is

log₂ K_(NZ,union)

where K_(NZ,union) is the number of NZ coefficients across of all layers(i.e., it corresponds to a union of NZ coefficients across all layers).In one alternative, K_(NZ,union)=aK₀ where K₀=

β×2LM

<2LM and β is higher layer configured, and a is a fixed integer (e.g.a=1 or 2).

In one alternative Alt 0-2: A single strongest coefficient c_(l*,i*,m*)is determined/reported across all layers comprising a layer-group, wherel* is the index of the layer (within the layer-group) to which thestrongest coefficient belongs to. For layer l=l* within the layer-group,the index of the strongest coefficient c_(l*,i*,m*)=1 is reported (henceits amplitude and phase are not reported), and for layers l≠l* withinthe layer-group, the strongest coefficient c_(l,i*,m*) is not reported(hence, amplitude and phase are reported for all NZ coefficients forthose layers). The number of bits to report the strongest coefficient is

log₂ ν_(g)

+

log₂ K_(NZ,l*)

where

log₂ ν_(g)

bits are used to indicate the layer index l* within the layer-group g,ν_(g) is the number of layers in the layer-group g, and

log₂ K_(NZ,l*g) bits are used to indicate the index of the strongestcoefficient c_(l*,i*,m*), and K_(NZ,l*g) is the number of NZcoefficients for layer l* within the layer-group g. In one example, alayer group corresponds to non-overlapping and consecutive layer pairs.For example, layer pair (0,1) comprises one layer-group and layer pair(2,3) comprises another layer-group. In one alternative, K_(NZ,l*)=aK₀where K₀=

β×2LM

<2LM and β is higher layer configured, and a is a fixed integer (e.g.a=1 or 2).

In one alternative Alt 0-3: A single strongest coefficient c_(l,i*,m*)is determined/reported across all layers comprising a layer-group. Thestrongest coefficient c_(l,i*,m*) is common for all layers comprising alayer-group, i.e., index (i*, m*) of the strongest coefficient is thesame for all layers, which implies that c_(l,i*,m*)=1 for all l valuescomprising a layer-group. In one example, a layer group corresponds tonon-overlapping and consecutive layer pairs. For example, layer pair(0,1) comprises one layer-group and layer pair (2,3) comprises anotherlayer-group. The number of bits to report the strongest coefficient is

log₂ K_(NZ,union,g)

where K_(NZ,union,g) is the number of NZ coefficients across of alllayers comprising layer-group g (i.e., it corresponds to a union of NZcoefficients across all layers comprising layer-group g). In onealternative, K_(NZ,union,g)=aK₀ where K₀=

β×2LM

<2LM and β is higher layer configured, and a is a fixed integer (e.g.a=1 or 2).

In one alternative Alt 0-4: A strongest coefficient c_(l*,i*,m*) isdetermined/reported independently for each layer l=0,1, . . . ,ν−1(regardless of the ν or RI value). For each layer l, the index of thestrongest coefficient c_(l,i*,m*)=1 is reported (hence its amplitude andphase are not reported). The ν strongest coefficient indicators (SCIs)are reported separately. Let K_(NZ,l) be the number of NZ coefficientsfor layer l. Then,

log₂ K_(NZ,l)

bits are used to indicate the SCI for layer l. So, the total payload ofreporting SCIs for all ν layers is Σ_(l=0) ^(ν−1)

log₂ K_(NZ,l)

bits. In one alternative, K_(NZ,l)=aK₀ where K₀=

β×2LM

<2LM and β is higher layer configured, and a is a fixed integer (e.g.a=1 or 2).

In one alternative Alt 0-5: A strongest coefficient c_(l*,i*,m*) isdetermined/reported independently for each layer l=0,1, . . . ,ν−1(regardless of the ν or RI value). For each layer l, the index of thestrongest coefficient c_(l,i*,m*)=1 is reported (hence its amplitude andphase are not reported). The ν strongest coefficient indicators (SCIs)are reported jointly. Let K_(NZ,union) be the number of NZ coefficientsacross of all layers (i.e., it corresponds to a union of NZ coefficientsacross all layers). So, the total payload of reporting SCIs for all νlayers is either

$\left\lceil {\log_{2}\begin{pmatrix}K_{{NZ},{union}} \\v\end{pmatrix}} \right\rceil$bits assuming SCIs for any two-layers are different, or

$\left\lceil {\log_{2}\begin{pmatrix}{K_{{NZ},{union}} + v - 1} \\v\end{pmatrix}} \right\rceil = \left\lceil {\log_{2}\begin{pmatrix}{K_{{NZ},{union}} + v - 1} \\{K_{{NZ},{union}} - 1}\end{pmatrix}} \right\rceil$bits assuming SCIs for two layers can be the same. In one alternative,K_(NZ,union)=aK₀ where K₀=

β×2LM

<2LM and β is higher layer configured, and a is a fixed integer (e.g.a=1 or 2).

In one alternative Alt 0-6: For RI=1, strongest coefficient indicator(SCI) is a

log₂ K_(NZ)

-bit indicator. For RI>1, SCI is determined/reported independently foreach layer l=0,1, . . . ,ν−1 (regardless of the ν or RI value). For eachlayer l, the index of the strongest coefficient c_(l,i*,m*)=1 isreported (hence its amplitude and phase are not reported). The νstrongest coefficient indicators (SCIs) are reported separately(independently per layer). Let K_(NZ,tot) be the total number of NZcoefficients across of all layers. So, the payload of reporting SCI foreach layer is

log₂ K_(NZ,tot)

bits. In one alternative, K_(NZ,tot)=aK₀ where K₀=

β×2LM

<2LM and is higher layer configured, and a is a fixed integer (e.g. a=1or 2).

In one alternative Alt 0-7: For RI=1, strongest coefficient indicator(SCI) is a

log₂ K_(NZ)

-bit indicator. For RI>1, SCI is determined/reported independently foreach layer l=0,1, . . . ,ν−1 (regardless of the ν or RI value). For eachlayer l, the index of the strongest coefficient c_(l,i*,m*)=1 isreported (hence its amplitude and phase are not reported). The νstrongest coefficient indicators (SCIs) are reported separately(independently per layer). Let K_(NZ,tot)=Σ_(l=0) ^(RI−1)K_(NZ,l) be thetotal number of NZ coefficients across of all layers. So, the payload ofreporting SCI for each layer is

log₂ min(K_(NZ,tot), 2L_(l)M_(l))

=

log₂ min(Σ_(l=0) ^(RI−1)K_(NZ,l), 2L_(l)M_(l))

bits, where 2L_(l)M_(l) is the size (number of bits) of the bitmapindicating the locations (indices) of NZ coefficients for layer l. Inone example, L_(l)=L for all l.

In one alternative Alt 0-8: For RI=1, strongest coefficient indicator(SCI) is a

log₂ K_(NZ)

-bit indicator. For RI>1, SCI is determined/reported independently foreach layer l=0,1, . . . ,ν−1 (regardless of the ν or RI value). For eachlayer l, the index of the strongest coefficient c_(l,i*,m*)=1 isreported (hence its amplitude and phase are not reported). The νstrongest coefficient indicators (SCIs) are reported separately(independently per layer). The payload of reporting SCI for each layeris

log₂ 2L_(l)

bits, which indicates the SD beam index i* of the strongest coefficient.The FD beam index m* is fixed, e.g., m*=1. In one example, L_(l)=L forall l.

Let K_(NZ,l) be the number of NZ coefficients reported by the UE forlayer l∈{0,1, . . . ,ν−1}, and let K_(NZ,tot)=Σ_(l=0) ^(ν−1)K_(NZ,l) bethe total number of NZ coefficients across ν layers.

In one embodiment 0A, a UE is configured to report the number of NZcoefficients for each layer independently (e.g. via UCI part 1). Foreach l∈{0,1, . . . ,ν−1}, the UE reports K_(NZ,l) using

log₂ K₀

bits indication where K₀ is the maximum number of NZ coefficients thatthe UE can report for each layer, so the total payload (number of bits)for this reporting is ν×

log₂ K₀. Alternatively, for each l∈{0,1, . . . ,ν−1}, the UE reportsK_(NZ,l) using

log₂ K_(0,l)

bits indication where K_(0,l) is the maximum number of NZ coefficientsthat the UE can report for layer l, so the total payload (number ofbits) for this reporting is Σ_(l=0) ^(ν−1)

log₂ K_(0,l)

. The value K₀=

β×2LM

<2LM and β is higher layer configured. Likewise, the value K_(0,l)=

β_(l)×2LM

<2LM and β_(l) is higher layer configured for each l. In one example,β₀=β₁, β₂=β₃ and β₀≠β₂, and both β₀ and β₂ are higher layer configured.In another example, β₀ is higher layer configured, and β₁, β₂ and β₃ aredetermined based on the configured β₀ value. In one example, the bitmapfor each layer is reported via UCI part 1 of a two-part UCI.

For layer l, the UE is further configured to report a size 2LM bitmapB_(l) comprising K_(NZ,l) ones “1” indicating the location of NZcoefficients. Alternatively, for layer l, the UE is further configuredto report a size 2LM bitmap B_(l) comprising K_(NZ,l) zeros “0”indicating the location of NZ coefficients. In one example, the bitmapfor each layer is reported via UCI part 2 of a two-part UCI. So, thetotal payload (number of bits) for this reporting is ν×2LM. Here, it isassumed that (L, M) is common for all layers. Alternatively, if (L,M)=(L_(l), M_(l)) for layer l, then the total payload (number of bits)for this reporting is Σ_(l=0) ^(ν−1)2L_(l)M_(l).

Furthermore, the UE is further configured to report a strongestcoefficient indicator (SCI) Il using

log₂ K_(NZ,l)

bits that indicates the location (index) of the strongest coefficient.In one example, the SCI for each layer is reported via UCI part 2 of atwo-part UCI. So, the total payload (number of bits) for this reportingis Σ_(l=0) ^(ν−1)

log₂ K_(NZ,l)

Finally, the UE is further configured to report amplitude and phase ofall NZ coefficients except the strongest coefficients. Assuming Scheme 1for amplitude and phase reporting, for each layer l, the UE reports areference amplitude using 4 bits, (K_(NZ,l)−1) differential amplitudeusing 3 bits for each, and (K_(NZ,l)−1) phase values using P∈{3,4} bitsfor each. So, for layer l, the total payload (number of bits) forreporting is 4+3(K_(NZ,l)−1)+P(K_(NZ,l)−1)=3K_(NZ,l)+1+P(K_(NZ,l)−1).And the total payload across all layers is3K_(NZ,tot)+ν+P(K_(NZ,tot)−ν).

In one variation of embodiment 0A, when the UE is configured with maxRI>1, then RI is reported according to at least one of the followingalternatives.

In one alternative Alt 0A-0: RI is reported as a separate UCI parameter(e.g. UCI part 1).

In one alternative Alt 0A-1: RI is not reported explicitly as a separateUCI parameter, and RI is derived from the number of NZ coefficients(K_(NZ,l)) reported independently for each layer l. Let RI_(max) be themaximum RI value configured to the UE. At least for one of thesub-alternatives is used.

In one alternative Alt 0A-1-0: for each layer l∈{0,1, . . .,RI_(max)−1}, the UE reports K_(NZ,l)∈{0,1,2, . . . , K₀} using

log₂(K₀+1)

bits indication.

In one alternative Alt 0A-1-1: for layer l=0, the UE reportsK_(NZ,l)∈{1,2, . . . , K₀} using

log₂ K₀

bits indication, and for each layer l∈{1, . . . , RI_(max)−1}, the UEreports K_(NZ,l)∈{0,1,2, . . . , K₀} using

log₂(K₀+1)

bits indication.

In one alternative Alt 0A-1-2: for layer l=0, the UE reportsK_(NZ,l)∈{1,2, . . . , K₀} using

log₂ K₀

bits indication, and for each layer l∈{1, . . . , RI_(max)−1}, the UEreports K_(NZ,l)∈{0,1,2, . . . , K₀−1} using

log₂ K₀

bits indication.

In another variation of embodiment 0A, the bitmap to report the indicesof NZ coefficients (e.g. via UCI part 2) is determined/reported asfollows. When RI∈{1,2}, then for each layer l∈{0, . . . , RI−1}, abitmap B_(l) comprising 2LM bits is reported by the UE. When RI∈{3,4},then the bitmap is determined/reported according to at least one of thefollowing alternatives.

In one alternative Alt 0A-2: for each layer l∈{0, . . . , RI−1}, abitmap B_(l) comprising 2LM_(l) bits is reported by the UE, where M_(l)is a number of FD basis vectors (beams) for layer l.

In one alternative Alt 0A-3: a X-bit bitmap is reported via UCI part 1to indicate layers whose coefficients corresponding to the “weak”antenna polarization (at the gNB) are dropped (i.e., coefficients areset zero), and for each layer l∈{0, . . . , RI−1}, a bitmap B_(l)comprising y×LM_(l) bits is reported by the UE, where y=1 if the weakpolarization coefficients are dropped, and y=2 otherwise (if the weakpolarization coefficients are not dropped).

In one embodiment 0B, a UE is configured to report a single SCI (insteadof ν SCIs in embodiment 0A) in UCI part 2 using

log₂ K_(NZ,l*)

bits that indicates the location (index) of the strongest coefficientfor layer l*. The UE is further configured to report a layer indicator J(e.g. using

log₂ ν

bits) to indicate the layer index l* to which the strongest coefficientbelongs to. This indication is in UCI part 1. The UE reports the numberof NZ coefficients for each layer independently, and bitmaps B_(l)indicating the location of NZ coefficients for each layer l, details ofwhich are the same as in embodiment 0A.

Finally, the UE is further configured to report amplitude and phase ofall NZ coefficients expect the strongest coefficients. Assuming Scheme 1for amplitude and phase reporting, for layer l=l*, the UE reports areference amplitude using 4 bits, (K_(NZ,l)−1) differential amplitudeusing 3 bits for each, and (K_(NZ,l)−1) phase values using P∈{3,4} bitsfor each. So, for layer l=l*, the total payload (number of bits) forreporting is 4+3(K_(NZ,l)−1)+P(K_(NZ,l)−1)=3K_(NZ,l)+1+P(K_(NZ,l)−1).for layer l≠l*, the UE reports a reference amplitude using 4 bits,K_(NZ,l) differential amplitude using 3 bits for each, and K_(NZ,l)phase values using P∈{3,4} bits for each. So, for layer l≠l*, the totalpayload (number of bits) for reporting is 4+3K_(NZ,l)+PK_(NZ,l).

In one embodiment 0C, a UE is configured to report the total (sum)number of NZ coefficients (K_(NZ,tot)) across all layers (e.g. via UCIpart 1). The UE reports K_(NZ,tot) using

log₂ aK₀

bits indication where K₀ is the maximum number of NZ coefficients thatthe UE can report for each layer, and a is a fixed integer depending onthe max RI value that the UE can report (e.g. based on the RIrestriction via higher layer signaling). For example,

When max RI=1, then a=1.

When max RI>1, then a=2.

In another example, the UE reports K_(NZ,tot) using

log₂ Σ_(l=0) ^(ν−1)K_(0,l)

bits indication where K_(0,l) is the maximum number of NZ coefficientsthat the UE can report for layer l. The value K₀=

β×2LM

<2LM and is β higher layer configured. Likewise, the value K_(0,l)=

β×2LM

<2LM and β_(l) is higher layer configured for each l. In one example,β₀=β₁, β₂=β₃ and β₀≠β₂, and both β₀ and β₂ are higher layer configured.In another example, β₀ is higher layer configured, and β₁, β₂ and β₃ aredetermined based on the configured β₀ value. In one example, the bitmapfor each layer is reported via UCI part 1 of a two-part UCI.

The UE is further configured to report a single 2LM×ν bitmap Bcomprising K_(NZ,tot) ones “1” indicating the location of NZcoefficients. Alternatively, the UE is further configured to report asingle 2LM×ν bitmap B comprising K_(NZ,l) zeros “0” indicating thelocation of NZ coefficients. In one example, the bitmap B is reportedvia UCI part 2 of a two-part UCI. So, the total payload (number of bits)for this reporting is ν×2LM. Here, it is assumed that (L, M) is commonfor all layers. Alternatively, if (L, M)=(L_(l), M_(l)) for layer l,then size of the bitmap is Σ_(l=0) ^(ν−1)2L_(l)M_(l), and hence thetotal payload (number of bits) for this reporting is Σ_(l=0)^(ν−1)2L_(l)M_(l). In one example, the bitmap B is concatenated acrosslayers, i.e., B=B₀, . . . B_(ν−1) where B_(l) is a bitmap for layer l,and B_(l)=B_(l,0)B_(l,1) . . . B_(l,M) _(l) ⁻¹ is concatenated acrosscolumns (FD index), or B_(l)=B_(l,0)B_(l,1) . . . B_(l,L) _(l) ⁻¹ isconcatenated across rows (SD index). In another example, the bitmap B isconcatenated first across rows (SD index) then across columns (FD index)then across layers. In another example, the bitmap B is concatenatedfirst across columns (FD index) then across rows (SD index) then acrosslayers. A few other examples of bitmap are as follows where the notation“A→B” indicates A precedes B in ordering.

Layer→rows→columns

Layer→columns→rows

Columns→layers→rows

Columns→rows→layers

Rows→layers→columns

Rows→columns→layers.

Furthermore, the UE is further configured to report a single strongestcoefficient indicator (SCI) across all layers using

log₂ K_(NZ,tot)

bits that indicates the location (index) of the strongest coefficientacross all layers. In one example, the SCI is reported via UCI part 2 ofa two-part UCI.

Finally, the UE is further configured to report amplitude and phase ofall NZ coefficients expect the strongest coefficients. Assuming Scheme 1for amplitude and phase reporting, the UE reports a reference amplitudeusing 4 bits, (K_(NZ,tot)−1) differential amplitude using 3 bits foreach, and (K_(NZ,tot)−1) phase values using P∈{3,4} bits for each. So,the total payload (number of bits) for reporting is4+3(K_(NZ,tot)−1)+P(K_(NZ,tot)−1)=3K_(NZ,tot)+1+P(K_(NZ,tot)−1).

In one variation of embodiment 0C, when the UE is configured with maxRI>1, then K_(NZ,tot) is reported according to at least one of thefollowing alternatives.

In one alternative Alt 0C-0: When UE reports RI=1, then the UE reportsK_(NZ,tot)∈{0,1,2, . . . ,K₀} using

log₂(K₀+1)

bits indication, and when UE reports RI>1, then the UE reportsK_(NZ,tot)∈{0,1,2, . . . , 2K₀} using

log₂(2K₀+1)

bits indication, where K_(NZ,tot)=0 indicates SD/FD basis insufficiency.

In one alternative Alt 0C-1: When UE reports RI=1, then the UE reportsK_(NZ,tot)∈{1,2, . . . ,K₀} using

log₂(K₀)

bits indication, and when UE reports RI>1, then UE reportsK_(NZ,tot)∈{1,2, . . . , 2K0} using

log₂(2K₀)

or 1+

log₂(K₀)

bits indication. Alternatively, when UE reports RI>1, then UE reportsK_(NZ,tot)∈{RI, RI+1, . . . , 2K₀} using

log₂(2K₀−RI+1)

bits indication.

In another variation of embodiment OC, when the UE is configured withmax RI>1, then K_(NZ,tot) is reported in a differential manner such thatK_(NZ,tot) comprises RI components K_(NZ,0), K_(NZ,1), . . .K_(NZ,RI−1), where K_(NZ,0) is a reference component and indicates anumber of NZ coefficients for layer 0.

For each layer l∈{1, . . . , RI−1}, K_(NZ,l) is a differential componentand indicates a differential number of NZ coefficients for layer l. Inone example, the actual number of NZ coefficients for layer l isK_(NZ,0)+K_(NZ,l).

In one example, K_(NZ,l)=α×2K₀, where α<1 is a fraction, and is eitherfixed, or configured or reported by the UE. In another example,K_(NZ,l)∈{0,1, . . . , x−1}, where x is either fixed, or configured, orreported by the UE.

In another variation of embodiment 0C, when the UE is configured withmax RI>1, then K_(NZ,tot) is reported in a differential manner such thatK_(NZ,tot) comprises a reference component K_(NZ,ref) and RIdifferential components K_(NZ,0), K_(NZ,1), . . . , K_(NZ,RI−1), where

K_(NZ,0) indicates a total number of NZ coefficients for all layers.Alternatively, K_(NZ,0) indicates a number of NZ coefficients that are aunion of NZ coefficients for all layers.

For each layer l∈{0,1, . . . , RI−1}, K_(NZ,l) indicates a differentialnumber of NZ coefficients for layer l. In one example, the actual numberof NZ coefficients for layer l is K_(NZ,0)−K_(NZ,l).

In one example, K_(NZ,l)=α×2K₀, where α<1 is a fraction, and is eitherfixed, or configured or reported by the UE. In another example,K_(NZ,l)∈{0,1, . . . , x−1}, where x is either fixed, or configured, orreported by the UE. In one example, K_(NZ,0)∈{1, . . . ,2K₀}.

In one embodiment 0D, a UE is configured to report the total (sum)number of NZ coefficients (K_(NZ,tot)) across all layers (e.g., via UCIpart 1) as explained in embodiment 0C. For each layer l, the UE isfurther configured to report the following (e.g. via UCI part 2):

Number of NZ coefficients K_(NZ,l) (e.g. via UCI part 2) so that theirsum Σ_(l=0) ^(ν−1)K_(NZ,l)=K_(NZ,tot),

Bitmap B_(l) as in embodiment 0A,

SCI where the payload (bits) for SCI reporting is fixed regardless ofthe reported K_(NZ,l) value, and

Amplitude and phase as in embodiment 0A.

In a variation, the number of NZ coefficients K_(NZ,i) is not reportedby the UE.

In one embodiment 0E, a UE is configured to report CSI in layer-groupswhere layer-groups are according to some embodiments in this disclosure(e.g. embodiment X). For a layer-group g, the UE is configured to CSIcomponents such as number of NZ coefficients, bitmap, strongestcoefficient indicator and amplitude/phase according to at least one ofembodiment 0/0A/0B/0C/0D. For any two layer-groups, the UE reports thesecomponents independently, i.e., the UE reports these components for eachlayer-group.

In one embodiment 0F, when RI>1, a UE is configured to report either thetotal (sum) number of NZ coefficients (K_(NZ,tot)=Σ_(l=0)^(RI−1)K_(NZ,l)) across all layers or per layer number of NZcoefficients (K_(NZ,l)) (e.g., via UCI part 1) as explained in some ofthe embodiments of this disclosure, where per layer K_(NZ,l) isaccording to at least one of the following alternatives.

In one alternative Alt 0F-0: K_(NZ,l) is unrestricted such that Σ_(l=0)^(RI−1)K_(NZ,l)≤2K₀

In one alternative Alt 0F-1: K_(NZ,l) is restricted such thatK_(NZ,l)≤K₀ and Σ_(l=0) ^(RI−1)K_(NZ,l)≤2K₀

In one embodiment 1, when rank>1, e.g., RI E {2,3,4}, the referenceamplitude p_(l,i,m) ⁽¹⁾ for the other antenna polarization (for thepolarization not associated with the strongest coefficient as explainedin Scheme 1) is determined/reported according to at least one of thefollowing alternatives (Alt). If multiple alternatives are supported,then at least one of the supported alternatives is either configured(e.g. via higher layer RRC signaling) or reported by the UE.

In one alternative Alt 1-0: A single reference amplitude p_(l*,i,m) ⁽¹⁾is determined/reported across all layers (i.e., regardless of the ν orRI value) where l* is the index of the layer to which the referenceamplitude belongs to. For layer l=l*, the reference amplitude p_(l*,i,m)⁽¹⁾ is reported, and for layers l≠l*, the reference amplitude p_(l,i,m)⁽¹⁾ is not reported and it is assumed to be a fixed value (e.g.,p_(l,i,m) ⁽¹⁾=1). The number of bits to report the reference amplitudeis A, where A=4 in one example.

In one alternative Alt 1-1: A single reference amplitude p_(l,i,m) ⁽¹⁾is determined/reported across all layers (i.e., regardless of the ν orRI value). The single reference amplitude p_(l,i,m) ⁽¹⁾ is common forall layers, i.e., it is the same for all layers. The number of bits toreport the reference amplitude is A, where A=4 in one example.

In one alternative Alt 1-2: A reference amplitude p_(l*,i,m) ⁽¹⁾ isdetermined/reported across all layers comprising a layer-group, where l*is the index of the layer (within the layer-group) to which thereference amplitude belongs to. For layer l=l* within the layer-group,the reference amplitude p_(l*,i,m) ⁽¹⁾ is reported, and for layers l≠l*within the layer-group, the reference amplitude) p_(l,i,m) ⁽¹⁾ notreported and it is assumed to be a fixed value (e.g., p_(l,i,m) ⁽¹⁾=1).The number of bits to report the reference amplitude is A×G, whereG=number of layer-groups, and A=4 in one example. In one example, alayer group corresponds to non-overlapping and consecutive layer pairs.For example, layer pair (0,1) comprises one layer-group and layer pair(2,3) comprises another layer-group.

In one alternative Alt 1-3: A single reference amplitude p_(l,i,m) ⁽¹⁾is determined/reported) across all layers comprising a layer-group. Thesingle reference amplitude p_(l,i,m) ⁽¹⁾ is common for all layerscomprising a layer-group, i.e., it is the same for all layers comprisinga layer-group. The number of bits to report the reference amplitude isA×G, where G=number of layer-groups, and A=4 in one example. In oneexample, a layer group corresponds to non-overlapping and consecutivelayer pairs. For example, layer pair (0,1) comprises one layer-group andlayer pair (2,3) comprises another layer-group.

In one alternative Alt 1-4: A single reference amplitude p_(l,i,m) ⁽¹⁾is determined/reported independently for each layer l=0,1, . . . ,ν−1(regardless of the ν or RI value). The number of bits to report thereference amplitude is A×ν, where A=4 in one example.

In one embodiment 2, when rank>1, e.g. RI∈{2,3,4}, the FD unit index m*(whose coefficients {c_(l,i,m*)i≠i*} are assigned more bits foramplitude and phase reporting in Scheme 2) is determined according to atleast one of the following alternatives (Alt). If multiple alternativesare supported, then at least one of the supported alternatives is eitherconfigured (e.g. via higher layer RRC signaling) or reported by the UE.

In one alternative Alt 2-0: the FD unit index m* is determined commonfor all layers, i.e., it is the same for all layers.

In one alternative Alt 2-1: the FD unit index m* is determinedindependently for each layer.

In one alternative Alt 2-2: the FD unit index m* is determinedindependently for each layer-group, and within a layer-group, the FDunit index m* is common for all layers comprising the layer-group. Inone example, a layer group corresponds to non-overlapping andconsecutive layer pairs. For example, layer pair (0,1) comprises onelayer-group and layer pair (2,3) comprises another layer-group.

In one embodiment X, a layer-group in embodiment 0/1/2 of thisdisclosure corresponds to non-overlapping and consecutive layer pairs. Afew examples of layer-groups are as follows depending on the RI value.

In one example Ex X-0: if the UE is configured to report a maximum valuefor RI=1, when the UE reports RI=1, there is only one layer-groupcomprising layer 0.

In one example Ex X-1: if the UE is configured to report a maximum valuefor RI=2, when the UE reports RI=1, there is only one layer-groupcomprising layer 0, and when the UE reports RI=2, there is only onelayer-group comprising layers 0.

In one example Ex X-2: if the UE is configured to report a maximum valuefor RI=3, then when the UE reports RI=1, there is only one layer-groupcomprising layer 0, when the UE reports RI=2, there is only onelayer-group comprising layers 0 and 1, and when the UE reports RI=3,there are two layer-groups, layer-group 0 comprising layers 0 and 1, andlayer-group 1 comprising layer 2.

In one example Ex X-3: if the UE is configured to report a maximum valuefor RI=4, when the UE reports RI=1, there is only one layer-groupcomprising layer 0, when the UE reports RI=2, there is only onelayer-group comprising layers 0 and 1, when the UE reports RI=3, thereare two layer-groups, layer-group 0 comprising layers 0 and 1, andlayer-group 1 comprising layer 2, and when the UE reports RI=4, thereare two layer-groups, layer-group 0 comprising layers 0 and 1, andlayer-group 1 comprising layers 2 and 3.

FIG. 14 illustrates a flow chart of a method 1400 for operating a userequipment (UE) for channel state information (CSI) feedback in awireless communication system, as may be performed by a UE, according toembodiments of the present disclosure. The embodiment of the method 1400illustrated in FIG. 14 is for illustration only. FIG. 14 does not limitthe scope of this disclosure to any particular implementation.

As illustrates in FIG. 14 , the method 1400 begins at step 1402. In step1402, the UE (e.g., 111-116 as illustrated in FIG. 1 ) receives, from abase station (BS), CSI reference signals (CSI-RSs) and CSI feedbackconfiguration information.

In step 1404, the UE estimates a channel based on the received CSI-RSs.

In step 1406, the UE determines, based on the estimated channel and theCSI feedback configuration information, a number of non-zerocoefficients (K_(l) ^(NZ)) for each layer (l) of a total number of υlayers, where υ≥1 is a rank value, and a sum of the K_(l) ^(NZ) acrosseach of the v layers as a total number of non-zero coefficients(K^(NZ)), where K^(NZ)=Σ_(l=1) ^(υ)K_(l) ^(NZ).

In step 1408, the UE transmits, to the BS, the CSI feedback includingthe K^(NZ) value over an uplink (UL) channel.

In one embodiment, a maximum number of non-zero coefficients the UE canreport per layer is K₀ such that K_(l) ^(NZ)≤K₀.

In one embodiment, the CSI feedback configuration information includes amaximum allowed value for υ. When the maximum allowed value for υ isgreater than 1, a maximum value for the K^(NZ) the UE can report is 2K₀such that K^(NZ)≤2K₀, and a number of bits for the UE to report theK^(NZ) is

log₂(2K₀)

where

is a ceiling function.

In one embodiment, the CSI feedback configuration information includes amaximum allowed value for υ. When the maximum allowed value for υ isequal to 1, a maximum value for the K^(NZ) the UE can report is K₀ suchthat K^(NZ)≤K₀, and a number of bits for the UE to report the K^(NZ) is

log₂(K₀)

where

is a ceiling function.

In one embodiment, K₀=

β×2LM

, where

is a ceiling function, β<1 is a higher layer configured parameter, and2LM is a total number of coefficients for each layer l, where a total of2LM coefficients form a 2L×M coefficient matrix C_(l) comprising 2L rowsand M columns, the K_(l) ^(NZ) non-zero coefficients correspond tonon-zero coefficients of the 2L×M coefficient matrix C_(l), and theremaining 2LM−K_(l) ^(NZ) coefficients of the 2L×M coefficient matrixC_(l) are zero.

In one embodiment, the CSI feedback includes a precoding matrixindicator (PMI) indicating the 2L×M coefficient matrix C_(l), a spatialdomain (SD) basis matrix A_(l) and a frequency domain (FD) basis matrixB_(l) for each l=1, . . . ,ν, and where a precoding matrix for each FDunit of a total number (N₃) of FD units is determined by columns of

$W = {\frac{1}{\sqrt{v}}\left\lbrack \begin{matrix}W^{1} & W^{2} & \cdots & \left. W^{v} \right\rbrack\end{matrix} \right.}$where

${W^{l} = {{\begin{bmatrix}A_{l} & 0 \\0 & A_{l}\end{bmatrix}C_{l}B_{l}^{H}} = \begin{bmatrix}{\overset{M - 1}{\sum\limits_{k = 0}}{\overset{L - 1}{\sum\limits_{i = 0}}{c_{l,i,k}\left( {a_{l,i}b_{l,k}^{H}} \right)}}} \\{\overset{M - 1}{\sum\limits_{k = 0}}{\overset{L - 1}{\sum\limits_{i = 0}}{c_{l,{i + L},k}\left( {a_{l,i}b_{l,k}^{H}} \right)}}}\end{bmatrix}}},{A_{l} = \left\lbrack {a_{l,0}a_{l,1}\ldots a_{l,{L - 1}}} \right\rbrack},{a_{l,i}{is}aN_{1}N_{2} \times 1}$column vector for SD antenna ports where N₁ and N₂ are number of antennaports, respectively, with a same antenna polarization in a first and asecond dimensions of a two-dimensional dual-polarized CSI-RS antennaports at the BS; B_(l)=[b_(l,0) b_(l,1) . . . b_(l,M−1)], b_(i,k) is aN₃×1 column vector for FD units, the 2L×M matrix C_(l) comprisescoefficients c_(i,i,k); and a number (L) of column vectors for the SDantenna ports, a number (M) of column vectors for the FD units, and thetotal number (N₃) of the FD units are configured via higher layersignaling.

In one embodiment, the CSI feedback is partitioned into two parts, CSIpart 1 and CSI part 2, CSI part 1 includes the K^(NZ) value and istransmitted via a UL control information (UCI) part 1, and CSI part 2 istransmitted via a UCI part 2, where UCI part 1 and UCI part 2 are partsof a two-part UCI transmitted over the UL channel.

FIG. 15 illustrates a flow chart of another method 1500, as may beperformed by a base station (BS), according to embodiments of thepresent disclosure. The embodiment of the method 1500 illustrated inFIG. 15 is for illustration only. FIG. 15 does not limit the scope ofthis disclosure to any particular implementation.

As illustrated in FIG. 15 , the method 1500 begins at step 1502. In step1502, the BS (e.g., 101-103 as illustrated in FIG. 1 ), generates CSIfeedback configuration information.

In step 1504, the BS transmits, to a user equipment (UE), CSI referencesignals (CSI-RSs) and the CSI feedback configuration information.

In step 1506, the BS receives, from the UE over an uplink (UL) channel,a CSI feedback including a value for a total number of non-zerocoefficients (K^(NZ)) that is a sum of a number of non-zero coefficients(K_(l) ^(N)) across each layer (l) of a total number of υ layers, wherethe CSI feedback is based on the CSI-RSs and the CSI feedbackconfiguration information, K^(NZ)=Σ_(l=1) ^(υ)K_(l) ^(NZ), K_(l) ^(NZ)is a number of non-zero coefficients for layer l, and υ≥1 is a rankvalue.

In one embodiment, a maximum number of non-zero coefficients the UE canreport per layer is K₀ such that K_(l) ^(NZ)≤K₀.

In one embodiment, the CSI feedback configuration information includes amaximum allowed value for υ. When the maximum allowed value for υ isgreater than 1, a maximum value for the K^(NZ) the UE can report is 2K₀such that K^(NZ)≤2K₀, and a number of bits for the UE to report theK^(NZ) is

log₂(2K₀)

, where

is a ceiling function.

In one embodiment, the CSI feedback configuration information includes amaximum allowed value for υ. When the maximum allowed value for υ isequal to 1, a maximum value for the K^(NZ) the UE can report is K₀ suchthat K^(NZ)≤K₀, and a number of bits for the UE to report the K^(NZ) is

log₂(K₀)

, where

is a ceiling function.

In one embodiment, K₀=

β×2LM

, where

is a ceiling function, β<1 is a higher layer configured parameter, and2LM is a total number of coefficients for each layer l, where a total of2LM coefficients form a 2L×M coefficient matrix C_(l) comprising 2L rowsand M columns, the K_(l) ^(NZ) non-zero coefficients correspond tonon-zero coefficients of the 2L×M coefficient matrix C_(l), and theremaining 2LM−K_(l) ^(NZ) coefficients of the 2L×M coefficient matrixC_(l) are zero.

In one embodiment, the CSI feedback includes a precoding matrixindicator (PMI) indicating the 2L×M coefficient matrix C_(l), a spatialdomain (SD) basis matrix A_(l) and a frequency domain (FD) basis matrixB_(l) for each l=1, . . . ,ν. A precoding matrix for each FD unit of atotal number (N₃) of FD units is determined by columns of

$W = {\frac{1}{\sqrt{v}}\left\lbrack \begin{matrix}W^{1} & W^{2} & \cdots & \left. W^{v} \right\rbrack\end{matrix} \right.}$where

${W^{l} = {{\begin{bmatrix}A_{l} & 0 \\0 & A_{l}\end{bmatrix}C_{l}B_{l}^{H}} = \begin{bmatrix}{\overset{M - 1}{\sum\limits_{k = 0}}{\overset{L - 1}{\sum\limits_{i = 0}}{c_{l,i,k}\left( {a_{l,i}b_{l,k}^{H}} \right)}}} \\{\overset{M - 1}{\sum\limits_{k = 0}}{\overset{L - 1}{\sum\limits_{i = 0}}{c_{l,{i + L},k}\left( {a_{l,i}b_{l,k}^{H}} \right)}}}\end{bmatrix}}},{A_{l} = \left\lbrack {a_{l,0}a_{l,1}\ldots a_{l,{L - 1}}} \right\rbrack},$is a

N₁N₂×1 column vector for SD antenna ports where N₁ and N₂ are number ofantenna ports, respectively, with a same antenna polarization in a firstand a second dimensions of a two-dimensional dual-polarized CSI-RSantenna ports at the BS, B_(l)=[b_(l,0) b_(l,1) . . . b_(l,M−1)],b_(l,k) is a N₃×1 column vector for FD units, the 2L×M matrix C_(l)comprises coefficients c_(i,i,k), and a number (L) of column vectors forthe SD antenna ports, a number (M) of column vectors for the FD units,and the total number (N₃) of the FD units are configured via higherlayer signaling.

In one embodiment, the CSI feedback is partitioned into two parts, CSIpart 1 and CSI part 2, CSI part 1 includes the K^(NZ) value and istransmitted via a UL control information (UCI) part 1, and CSI part 2 istransmitted via a UCI part 2, where UCI part 1 and UCI part 2 are partsof a two-part UCI transmitted over the UL channel.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

None of the description in this application should be read as implyingthat any particular element, step, or function is an essential elementthat must be included in the claims scope. The scope of patented subjectmatter is defined only by the claims. Moreover, none of the claims areintended to invoke 35 U.S.C. § 112(f) unless the exact words “means for”are followed by a participle.

What is claimed is:
 1. A user equipment (UE) for channel stateinformation (CSI) feedback in a wireless communication system, the UEcomprising: a transceiver configured to receive, from a base station(BS), a CSI reference signal (CSI-RS) and CSI feedback configurationinformation; and a processor operably coupled to the transceiver, theprocessor configured to: measure a channel based on the CSI-RS receivedfrom the BS, and identify, based on the measured channel and the CSIfeedback configuration information, a total number of non-zerocoefficients summed across all layers, wherein the transceiver isfurther configured to transmit, to the BS, a CSI feedback indicating thetotal number of non-zero coefficients over an uplink (UL) channel,wherein a number of bits for reporting the total number of non-zerocoefficients summed across all the layers is

log₂ 2K₀

in case that a max allowed value of a rank indicator is greater than 1,and wherein K₀ corresponds to a max number of non-zero coefficients forone layer.
 2. The UE of claim 1, wherein the processor is furtherconfigured to: identify K_(NZ,l) based on the measured channel and theCSI feedback configuration information, and identify the total number ofnon-zero coefficients for all the layers as Σ_(l=0) ^(ν−1)K_(NZ,l), andwherein K_(NZ,l) corresponds to a number of nonzero coefficients foreach layer.
 3. The UE of claim 1, wherein the total number of non-zerocoefficients for all the layers is equal to or less than 2K₀.
 4. The UEof claim 3, wherein: K₀ is

β×2LM

, 2LM corresponds to a total number of coefficients for the one layer, βcorresponds to a higher layer parameter, and β is less than
 1. 5. The UEof claim 1, wherein: the CSI feedback is partitioned into two parts, CSIpart 1 and CSI part 2, and the CSI feedback indicating the total numberof non-zero coefficients is transmitted via the CSI part
 1. 6. The UE ofclaim 1, wherein the processor is further configured to identify thenumber of bits for reporting the total number of non-zero coefficientsbased on the CSI feedback configuration information including the maxallowed value of the rank indicator.
 7. The UE of claim 1, wherein: theprocessor is further configured to identify the number of bits forreporting the total number of non-zero coefficients based on 2K₀, incase that the max allowed value of the rank indicator is greater than 1,and 2K₀ corresponds to a max value for the total number of non-zerocoefficients summed across all layers.
 8. The UE of claim 1, wherein theprocessor is further configured to identify the number of bits forreporting the total number of non-zero coefficients as

log₂ K₀

, in case that the max allowed value of the rank indicator is equalto
 1. 9. A base station (BS) in a wireless communication system, the BScomprising: a processor configured to generate channel state information(CSI) feedback configuration information; and a transceiver operablyconnected to the processor, the transceiver to: transmit, to a userequipment (UE), a CSI reference signal (CSI-RS) and the CSI feedbackconfiguration information, and receive, from the UE over uplink (UL)channel, a CSI feedback indicating a total number of non-zerocoefficients summed across all layers, wherein the total number ofnon-zero coefficients is identified based on the CSI-RS and the CSIfeedback configuration information, wherein a number of bits forreporting the total number of non-zero coefficients summed across alllayers is

log₂ 2K₀

in case that a max allowed value of a rank indicator is greater than 1,and wherein K₀ corresponds to a max number of non-zero coefficients forone layer.
 10. The BS of claim 9, wherein: K_(NZ,l) is identified basedon the CSI-RS and the CSI feedback configuration information, the totalnumber of non-zero coefficients for all the layers is Σ_(l=0)^(ν−1)K_(NZ,l), and K_(NZ,l) corresponds to a number of nonzerocoefficients for each layer.
 11. The BS of claim 9, wherein the totalnumber of non-zero coefficients for all the layers is equal to or lessthan 2K₀.
 12. The BS of claim 11, wherein: K₀ is

β×2LM

, 2LM corresponds to a total number of coefficients for the one layer, βcorresponds to a higher layer parameter, and β is less than
 1. 13. TheBS of claim 9, wherein: the CSI feedback is partitioned into two parts,CSI part 1 and CSI part 2, and the CSI feedback indicating the totalnumber of non-zero coefficients is received via the CSI part
 1. 14. TheBS of claim 9, wherein the number of bits for reporting the total numberof non-zero coefficients is identified based on the CSI feedbackconfiguration information including a max allowed value of a rankindicator.
 15. The BS of claim 9, wherein: the number of bits forreporting the total number of non-zero coefficients is based on 2K₀, incase that the max allowed value of the rank indicator is greater than 1,and 2K₀ corresponds to a max value for the total number of non-zerocoefficients summed across all layers.
 16. The BS of claim 9, whereinthe number of bits for reporting the total number of non-zerocoefficients is

log₂ K₀

, in case that the max allowed value of the rank indicator is equalto
 1. 17. A method for operating a user equipment (UE) for a channelstate information (CSI) feedback in a wireless communication system, themethod comprising: receiving, from a base station (BS), a CSI referencesignal(CSI-RS) and CSI feedback configuration information; measuring achannel based on the CSI-RS received from the BS; identifying, based onthe measured channel and the CSI feedback configuration information, atotal number of non-zero coefficients summed across all layers; andtransmitting, to the BS, a CSI feedback indicating the total number ofnon-zero coefficients over an uplink (UL) channel, wherein a number ofbits for reporting the total number of non-zero coefficients summedacross all the layers is

log₂ 2K₀

in case that a max allowed value of a rank indicator is greater than 1,and wherein K₀ corresponds to a max number of non-zero coefficients forone layer.
 18. The method of claim 17, further comprising: identifyingK_(NZ,l) based on the measured channel and the CSI feedbackconfiguration information including a max allowed value of a rankindicator; and identifying the total number of non-zero coefficients forall the layers as Σ_(l=0) ^(ν−1)K_(NZ,l), wherein K_(NZ,l) correspondsto a number of nonzero coefficients for each layer.
 19. The method ofclaim 17, wherein the total number of non-zero coefficients for all thelayers is equal to or less than 2K₀.
 20. The method of claim 19,wherein: K₀ is

β×2LM

, 2LM corresponds to a total number of coefficients for the one layer, βcorresponds to a higher layer parameter, and β is less than 1.